feat(mcp): upgrade rmcp to 0.15.0 and advertise MCP Apps UI extension capability (#6927)

Cargo.lock

@@ -524,9 +524,9 @@ dependencies = [
 
 [[package]]
 name = "aws-smithy-async"
-version = "1.2.11"
+version = "1.2.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "52eec3db979d18cb807fc1070961cc51d87d069abe9ab57917769687368a8c6c"
+checksum = "3cba48474f1d6807384d06fec085b909f5807e16653c5af5c45dfe89539f0b70"
 dependencies = [
  "futures-util",
  "pin-project-lite",
@@ -693,9 +693,9 @@ dependencies = [
 
 [[package]]
 name = "aws-smithy-xml"
-version = "0.60.13"
+version = "0.60.14"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "11b2f670422ff42bf7065031e72b45bc52a3508bd089f743ea90731ca2b6ea57"
+checksum = "b53543b4b86ed43f051644f704a98c7291b3618b67adf057ee77a366fa52fcaa"
 dependencies = [
  "xmlparser",
 ]
@@ -1568,7 +1568,7 @@ dependencies = [
  "candle-kernels",
  "candle-metal-kernels",
  "candle-ug",
- "cudarc 0.19.1",
+ "cudarc 0.19.2",
  "float8 0.6.1",
  "gemm 0.19.0",
  "half",
@@ -2295,9 +2295,9 @@ dependencies = [
 
 [[package]]
 name = "cudarc"
-version = "0.19.1"
+version = "0.19.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "60d4882b3e023670c25b8a3e1ac97349070f8e5400807c091b70e0bdad6e9b93"
+checksum = "aed81f178e780f3d5d354d12b4c5c5a484c4a9c329ecd037ac57f2a0e0648397"
 dependencies = [
  "float8 0.7.0",
  "half",
@@ -2869,9 +2869,9 @@ dependencies = [
 
 [[package]]
 name = "deranged"
-version = "0.5.5"
+version = "0.5.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "ececcb659e7ba858fb4f10388c250a7252eb0a27373f1a72b8748afdd248e587"
+checksum = "cc3dc5ad92c2e2d1c193bbbbdf2ea477cb81331de4f3103f267ca18368b988c4"
 dependencies = [
  "powerfmt",
 ]
@@ -3491,7 +3491,7 @@ version = "0.6.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "719a903cc23e4a89e87962c2a80fdb45cdaad0983a89bd150bb57b4c8571a7d5"
 dependencies = [
- "cudarc 0.19.1",
+ "cudarc 0.19.2",
  "half",
  "num-traits",
  "rand 0.9.2",
@@ -4075,6 +4075,19 @@ dependencies = [
  "wasm-bindgen",
 ]
 
+[[package]]
+name = "getrandom"
+version = "0.4.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "139ef39800118c7683f2fd3c98c1b23c09ae076556b435f8e9064ae108aaeeec"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "r-efi",
+ "wasip2",
+ "wasip3",
+]
+
 [[package]]
 name = "gif"
 version = "0.13.3"
@@ -4176,7 +4189,7 @@ dependencies = [
  "rand 0.8.5",
  "regex",
  "reqwest 0.12.28",
- "rmcp 0.14.0",
+ "rmcp 0.15.0",
  "rubato",
  "schemars 1.2.1",
  "serde",
@@ -4234,7 +4247,7 @@ dependencies = [
  "goose-test-support",
  "http-body-util",
  "regex",
- "rmcp 0.14.0",
+ "rmcp 0.15.0",
  "sacp",
  "serde",
  "serde_json",
@@ -4277,7 +4290,7 @@ dependencies = [
  "open",
  "rand 0.8.5",
  "regex",
- "rmcp 0.14.0",
+ "rmcp 0.15.0",
  "rustyline",
  "serde",
  "serde_json",
@@ -4318,7 +4331,7 @@ dependencies = [
  "rayon",
  "regex",
  "reqwest 0.12.28",
- "rmcp 0.14.0",
+ "rmcp 0.15.0",
  "schemars 1.2.1",
  "serde",
  "serde_json",
@@ -4368,7 +4381,7 @@ dependencies = [
  "once_cell",
  "rand 0.9.2",
  "reqwest 0.12.28",
- "rmcp 0.14.0",
+ "rmcp 0.15.0",
  "rustls 0.23.36",
  "serde",
  "serde_json",
@@ -4405,7 +4418,7 @@ name = "goose-test-support"
 version = "1.23.0"
 dependencies = [
  "axum 0.7.9",
- "rmcp 0.14.0",
+ "rmcp 0.15.0",
  "serde_json",
  "tokio",
 ]
@@ -4985,6 +4998,12 @@ dependencies = [
  "zerovec",
 ]
 
+[[package]]
+name = "id-arena"
+version = "2.3.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3d3067d79b975e8844ca9eb072e16b31c3c1c36928edf9c6789548c524d0d954"
+
 [[package]]
 name = "ident_case"
 version = "1.0.1"
@@ -5458,9 +5477,9 @@ dependencies = [
 
 [[package]]
 name = "lazy-regex"
-version = "3.5.1"
+version = "3.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "c5c13b6857ade4c8ee05c3c3dc97d2ab5415d691213825b90d3211c425c1f907"
+checksum = "6bae91019476d3ec7147de9aa291cadb6d870abf2f3015d2da73a90325ac1496"
 dependencies = [
  "lazy-regex-proc_macros",
  "once_cell",
@@ -5469,9 +5488,9 @@ dependencies = [
 
 [[package]]
 name = "lazy-regex-proc_macros"
-version = "3.5.1"
+version = "3.6.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "32a95c68db5d41694cea563c86a4ba4dc02141c16ef64814108cb23def4d5438"
+checksum = "4de9c1e1439d8b7b3061b2d209809f447ca33241733d9a3c01eabf2dc8d94358"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -5488,6 +5507,12 @@ dependencies = [
  "spin",
 ]
 
+[[package]]
+name = "leb128fmt"
+version = "0.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "09edd9e8b54e49e587e4f6295a7d29c3ea94d469cb40ab8ca70b288248a81db2"
+
 [[package]]
 name = "lebe"
 version = "0.5.3"
@@ -5496,9 +5521,9 @@ checksum = "7a79a3332a6609480d7d0c9eab957bca6b455b91bb84e66d19f5ff66294b85b8"
 
 [[package]]
 name = "libc"
-version = "0.2.180"
+version = "0.2.181"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bcc35a38544a891a5f7c865aca548a982ccb3b8650a5b06d0fd33a10283c56fc"
+checksum = "459427e2af2b9c839b132acb702a1c654d95e10f8c326bfc2ad11310e458b1c5"
 
 [[package]]
 name = "libdbus-sys"
@@ -7333,9 +7358,9 @@ dependencies = [
 
 [[package]]
 name = "process-wrap"
-version = "9.0.1"
+version = "9.0.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "fd1395947e69c07400ef4d43db0051d6f773c21f647ad8b97382fc01f0204c60"
+checksum = "5811c133381ea59d7dd6ca37419b434bb2e3089a2a59c1e4b26a86fa79426e23"
 dependencies = [
  "futures",
  "indexmap 2.13.0",
@@ -7981,6 +8006,33 @@ name = "rmcp"
 version = "0.14.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "0a621b37a548ff6ab6292d57841eb25785a7f146d89391a19c9f199414bd13da"
+dependencies = [
+ "async-trait",
+ "base64 0.22.1",
+ "chrono",
+ "futures",
+ "http 1.4.0",
+ "pastey",
+ "pin-project-lite",
+ "process-wrap",
+ "reqwest 0.12.28",
+ "rmcp-macros 0.14.0",
+ "schemars 1.2.1",
+ "serde",
+ "serde_json",
+ "sse-stream",
+ "thiserror 2.0.18",
+ "tokio",
+ "tokio-stream",
+ "tokio-util",
+ "tracing",
+]
+
+[[package]]
+name = "rmcp"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1bef41ebc9ebed2c1b1d90203e9d1756091e8a00bbc3107676151f39868ca0ee"
 dependencies = [
  "async-trait",
  "axum 0.8.8",
@@ -7997,7 +8049,7 @@ dependencies = [
  "process-wrap",
  "rand 0.9.2",
  "reqwest 0.12.28",
- "rmcp-macros 0.14.0",
+ "rmcp-macros 0.15.0",
  "schemars 1.2.1",
  "serde",
  "serde_json",
@@ -8038,6 +8090,19 @@ dependencies = [
  "syn 2.0.114",
 ]
 
+[[package]]
+name = "rmcp-macros"
+version = "0.15.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0e88ad84b8b6237a934534a62b379a5be6388915663c0cc598ceb9b3292bbbfe"
+dependencies = [
+ "darling 0.23.0",
+ "proc-macro2",
+ "quote",
+ "serde_json",
+ "syn 2.0.114",
+]
+
 [[package]]
 name = "roff"
 version = "0.2.2"
@@ -9989,12 +10054,12 @@ dependencies = [
 
 [[package]]
 name = "tempfile"
-version = "3.24.0"
+version = "3.25.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "655da9c7eb6305c55742045d5a8d2037996d61d8de95806335c7c86ce0f82e9c"
+checksum = "0136791f7c95b1f6dd99f9cc786b91bb81c3800b639b3478e561ddb7be95e5f1"
 dependencies = [
  "fastrand",
- "getrandom 0.3.4",
+ "getrandom 0.4.1",
  "once_cell",
  "rustix 1.1.3",
  "windows-sys 0.61.2",
@@ -10448,9 +10513,9 @@ dependencies = [
 
 [[package]]
 name = "toml"
-version = "0.9.11+spec-1.1.0"
+version = "0.9.12+spec-1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "f3afc9a848309fe1aaffaed6e1546a7a14de1f935dc9d89d32afd9a44bab7c46"
+checksum = "cf92845e79fc2e2def6a5d828f0801e29a2f8acc037becc5ab08595c7d5e9863"
 dependencies = [
  "indexmap 2.13.0",
  "serde_core",
@@ -10472,9 +10537,9 @@ dependencies = [
 
 [[package]]
 name = "toml_parser"
-version = "1.0.6+spec-1.1.0"
+version = "1.0.7+spec-1.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a3198b4b0a8e11f09dd03e133c0280504d0801269e9afa46362ffde1cbeebf44"
+checksum = "247eaa3197818b831697600aadf81514e577e0cba5eab10f7e064e78ae154df1"
 dependencies = [
  "winnow",
 ]
@@ -10895,9 +10960,9 @@ checksum = "e7b17f197b3050ba473acf9181f7b1d3b66d1cf7356c6cc57886662276e65908"
 
 [[package]]
 name = "typed-path"
-version = "0.12.2"
+version = "0.12.3"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "3015e6ce46d5ad8751e4a772543a30c7511468070e98e64e20165f8f81155b64"
+checksum = "8e28f89b80c87b8fb0cf04ab448d5dd0dd0ade2f8891bae878de66a75a28600e"
 
 [[package]]
 name = "typeid"
@@ -11303,6 +11368,15 @@ dependencies = [
  "wit-bindgen",
 ]
 
+[[package]]
+name = "wasip3"
+version = "0.4.0+wasi-0.3.0-rc-2026-01-06"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5428f8bf88ea5ddc08faddef2ac4a67e390b88186c703ce6dbd955e1c145aca5"
+dependencies = [
+ "wit-bindgen",
+]
+
 [[package]]
 name = "wasite"
 version = "0.1.0"
@@ -11368,6 +11442,28 @@ dependencies = [
  "unicode-ident",
 ]
 
+[[package]]
+name = "wasm-encoder"
+version = "0.244.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "990065f2fe63003fe337b932cfb5e3b80e0b4d0f5ff650e6985b1048f62c8319"
+dependencies = [
+ "leb128fmt",
+ "wasmparser",
+]
+
+[[package]]
+name = "wasm-metadata"
+version = "0.244.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bb0e353e6a2fbdc176932bbaab493762eb1255a7900fe0fea1a2f96c296cc909"
+dependencies = [
+ "anyhow",
+ "indexmap 2.13.0",
+ "wasm-encoder",
+ "wasmparser",
+]
+
 [[package]]
 name = "wasm-streams"
 version = "0.4.2"
@@ -11391,6 +11487,18 @@ dependencies = [
  "thiserror 2.0.18",
 ]
 
+[[package]]
+name = "wasmparser"
+version = "0.244.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "47b807c72e1bac69382b3a6fb3dbe8ea4c0ed87ff5629b8685ae6b9a611028fe"
+dependencies = [
+ "bitflags 2.10.0",
+ "hashbrown 0.15.5",
+ "indexmap 2.13.0",
+ "semver",
+]
+
 [[package]]
 name = "web-sys"
 version = "0.3.85"
@@ -12119,6 +12227,88 @@ name = "wit-bindgen"
 version = "0.51.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "d7249219f66ced02969388cf2bb044a09756a083d0fab1e566056b04d9fbcaa5"
+dependencies = [
+ "wit-bindgen-rust-macro",
+]
+
+[[package]]
+name = "wit-bindgen-core"
+version = "0.51.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ea61de684c3ea68cb082b7a88508a8b27fcc8b797d738bfc99a82facf1d752dc"
+dependencies = [
+ "anyhow",
+ "heck",
+ "wit-parser",
+]
+
+[[package]]
+name = "wit-bindgen-rust"
+version = "0.51.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b7c566e0f4b284dd6561c786d9cb0142da491f46a9fbed79ea69cdad5db17f21"
+dependencies = [
+ "anyhow",
+ "heck",
+ "indexmap 2.13.0",
+ "prettyplease",
+ "syn 2.0.114",
+ "wasm-metadata",
+ "wit-bindgen-core",
+ "wit-component",
+]
+
+[[package]]
+name = "wit-bindgen-rust-macro"
+version = "0.51.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "0c0f9bfd77e6a48eccf51359e3ae77140a7f50b1e2ebfe62422d8afdaffab17a"
+dependencies = [
+ "anyhow",
+ "prettyplease",
+ "proc-macro2",
+ "quote",
+ "syn 2.0.114",
+ "wit-bindgen-core",
+ "wit-bindgen-rust",
+]
+
+[[package]]
+name = "wit-component"
+version = "0.244.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "9d66ea20e9553b30172b5e831994e35fbde2d165325bec84fc43dbf6f4eb9cb2"
+dependencies = [
+ "anyhow",
+ "bitflags 2.10.0",
+ "indexmap 2.13.0",
+ "log",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "wasm-encoder",
+ "wasm-metadata",
+ "wasmparser",
+ "wit-parser",
+]
+
+[[package]]
+name = "wit-parser"
+version = "0.244.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ecc8ac4bc1dc3381b7f59c34f00b67e18f910c2c0f50015669dde7def656a736"
+dependencies = [
+ "anyhow",
+ "id-arena",
+ "indexmap 2.13.0",
+ "log",
+ "semver",
+ "serde",
+ "serde_derive",
+ "serde_json",
+ "unicode-xid",
+ "wasmparser",
+]
 
 [[package]]
 name = "writeable"

Cargo.toml

@@ -15,7 +15,7 @@ uninlined_format_args = "allow"
 string_slice = "warn"
 
 [workspace.dependencies]
-rmcp = { version = "0.14.0", features = ["schemars", "auth"] }
+rmcp = { version = "0.15.0", features = ["schemars", "auth"] }
 anyhow = "1.0"
 async-stream = "0.3"
 async-trait = "0.1"

crates/goose-mcp/src/autovisualiser/mod.rs

@@ -417,6 +417,7 @@ impl ServerHandler for AutoVisualiserRouter {
                 name: "goose-autovisualiser".to_string(),
                 version: env!("CARGO_PKG_VERSION").to_owned(),
                 title: None,
+                description: None,
                 icons: None,
                 website_url: None,
             },

crates/goose-mcp/src/computercontroller/mod.rs

@@ -1301,6 +1301,7 @@ impl ServerHandler for ComputerControllerServer {
                 name: "goose-computercontroller".to_string(),
                 version: env!("CARGO_PKG_VERSION").to_owned(),
                 title: None,
+                description: None,
                 icons: None,
                 website_url: None,
             },

crates/goose-mcp/src/developer/rmcp_developer.rs

@@ -427,6 +427,7 @@ impl ServerHandler for DeveloperServer {
                 name: "goose-developer".to_string(),
                 version: env!("CARGO_PKG_VERSION").to_owned(),
                 title: None,
+                description: None,
                 icons: None,
                 website_url: None,
             },

crates/goose-mcp/src/memory/mod.rs

@@ -549,6 +549,7 @@ impl ServerHandler for MemoryServer {
                 name: "goose-memory".to_string(),
                 version: env!("CARGO_PKG_VERSION").to_owned(),
                 title: None,
+                description: None,
                 icons: None,
                 website_url: None,
             },

crates/goose-mcp/src/tutorial/mod.rs

@@ -114,6 +114,7 @@ impl ServerHandler for TutorialServer {
                 name: "goose-tutorial".to_string(),
                 version: env!("CARGO_PKG_VERSION").to_owned(),
                 title: None,
+                description: None,
                 icons: None,
                 website_url: None,
             },

crates/goose-server/src/openapi.rs

@@ -12,7 +12,7 @@ use goose::session::{Session, SessionInsights, SessionType, SystemInfo};
 use rmcp::model::{
     Annotations, Content, EmbeddedResource, Icon, ImageContent, JsonObject, RawAudioContent,
     RawEmbeddedResource, RawImageContent, RawResource, RawTextContent, ResourceContents, Role,
-    TextContent, Tool, ToolAnnotations,
+    TaskSupport, TextContent, Tool, ToolAnnotations, ToolExecution,
 };
 use utoipa::{OpenApi, ToSchema};
 
@@ -319,6 +319,8 @@ derive_utoipa!(RawEmbeddedResource as RawEmbeddedResourceSchema);
 derive_utoipa!(RawResource as RawResourceSchema);
 derive_utoipa!(Tool as ToolSchema);
 derive_utoipa!(ToolAnnotations as ToolAnnotationsSchema);
+derive_utoipa!(ToolExecution as ToolExecutionSchema);
+derive_utoipa!(TaskSupport as TaskSupportSchema);
 derive_utoipa!(Annotations as AnnotationsSchema);
 derive_utoipa!(ResourceContents as ResourceContentsSchema);
 derive_utoipa!(JsonObject as JsonObjectSchema);
@@ -497,6 +499,8 @@ derive_utoipa!(Icon as IconSchema);
         RecipeManifest,
         ToolSchema,
         ToolAnnotationsSchema,
+        ToolExecutionSchema,
+        TaskSupportSchema,
         ToolInfo,
         PermissionLevel,
         Permission,

crates/goose/src/agents/apps_extension.rs

@@ -131,11 +131,13 @@ impl AppsManagerClient {
                 experimental: None,
                 tasks: None,
                 logging: None,
+                extensions: None,
             },
             server_info: Implementation {
                 name: EXTENSION_NAME.to_string(),
                 title: Some("Apps Manager".to_string()),
                 version: "1.0.0".to_string(),
+                description: None,
                 icons: None,
                 website_url: None,
             },

crates/goose/src/agents/chatrecall_extension.rs

@@ -43,11 +43,12 @@ impl ChatRecallClient {
         let info = InitializeResult {
             protocol_version: ProtocolVersion::V_2025_03_26,
             capabilities: ServerCapabilities {
-                tasks: None,
                 tools: Some(ToolsCapability {
                     list_changed: Some(false),
                 }),
+                tasks: None,
                 resources: None,
+                extensions: None,
                 prompts: None,
                 completions: None,
                 experimental: None,
@@ -55,6 +56,7 @@ impl ChatRecallClient {
             },
             server_info: Implementation {
                 name: EXTENSION_NAME.to_string(),
+                description: None,
                 title: Some("Chat Recall".to_string()),
                 version: "1.0.0".to_string(),
                 icons: None,

crates/goose/src/agents/code_execution_extension.rs

@@ -56,11 +56,12 @@ impl CodeExecutionClient {
         let info = InitializeResult {
             protocol_version: ProtocolVersion::V_2025_03_26,
             capabilities: ServerCapabilities {
-                tasks: None,
                 tools: Some(ToolsCapability {
                     list_changed: Some(false),
                 }),
+                tasks: None,
                 resources: None,
+                extensions: None,
                 prompts: None,
                 completions: None,
                 experimental: None,
@@ -68,6 +69,7 @@ impl CodeExecutionClient {
             },
             server_info: Implementation {
                 name: EXTENSION_NAME.to_string(),
+                description: None,
                 title: Some("Code Mode".to_string()),
                 version: "1.0.0".to_string(),
                 icons: None,

crates/goose/src/agents/extension_manager.rs

@@ -925,6 +925,7 @@ impl ExtensionManager {
                                 input_schema: tool.input_schema,
                                 annotations: tool.annotations,
                                 output_schema: tool.output_schema,
+                                execution: tool.execution,
                                 icons: tool.icons,
                                 title: tool.title,
                                 meta: Some(rmcp::model::Meta(meta_map)),

crates/goose/src/agents/extension_manager_extension.rs

@@ -85,11 +85,12 @@ impl ExtensionManagerClient {
         let info = InitializeResult {
             protocol_version: ProtocolVersion::V_2025_03_26,
             capabilities: ServerCapabilities {
-                tasks: None,
                 tools: Some(ToolsCapability {
                     list_changed: Some(false),
                 }),
+                tasks: None,
                 resources: None,
+                extensions: None,
                 prompts: None,
                 completions: None,
                 experimental: None,
@@ -97,6 +98,7 @@ impl ExtensionManagerClient {
             },
             server_info: Implementation {
                 name: EXTENSION_NAME.to_string(),
+                description: None,
                 title: Some(EXTENSION_NAME.to_string()),
                 version: "1.0.0".to_string(),
                 icons: None,

crates/goose/src/agents/mcp_client.rs

@@ -2,8 +2,8 @@ use crate::action_required_manager::ActionRequiredManager;
 use crate::agents::types::SharedProvider;
 use crate::session_context::{SESSION_ID_HEADER, WORKING_DIR_HEADER};
 use rmcp::model::{
-    Content, CreateElicitationRequestParams, CreateElicitationResult, ElicitationAction, ErrorCode,
+    CreateElicitationRequestParams, CreateElicitationResult, ElicitationAction, ErrorCode,
-    Extensions, JsonObject, Meta,
+    ExtensionCapabilities, Extensions, JsonObject, Meta, SamplingMessageContent,
 };
 /// MCP client implementation for Goose
 use rmcp::{
@@ -223,9 +223,9 @@ impl ClientHandler for GooseClient {
                     Role::Assistant => crate::conversation::message::Message::assistant(),
                 };
 
-                match msg.content.as_text() {
+                match msg.content.first().and_then(|c| c.as_text()) {
                     Some(text) => base.with_text(&text.text),
-                    None => base.with_content(msg.content.clone().into()),
+                    None => base,
                 }
             })
             .collect();
@@ -255,29 +255,26 @@ impl ClientHandler for GooseClient {
         Ok(CreateMessageResult {
             model: usage.model,
             stop_reason: Some(CreateMessageResult::STOP_REASON_END_TURN.to_string()),
-            message: SamplingMessage {
+            message: SamplingMessage::new(
-                role: Role::Assistant,
+                Role::Assistant,
-                // TODO(alexhancock): MCP sampling currently only supports one content on each SamplingMessage
+                if let Some(content) = response.content.first() {
-                // https://modelcontextprotocol.io/specification/draft/client/sampling#messages
-                // This doesn't mesh well with goose's approach which has Vec<MessageContent>
-                // There is a proposal to MCP which is agreed to go in the next version to have SamplingMessages support multiple content parts
-                // https://github.com/modelcontextprotocol/modelcontextprotocol/pull/198
-                // Until that is formalized, we can take the first message content from the provider and use it
-                content: if let Some(content) = response.content.first() {
                     match content {
                         crate::conversation::message::MessageContent::Text(text) => {
-                            Content::text(&text.text)
+                            SamplingMessageContent::text(&text.text)
                         }
                         crate::conversation::message::MessageContent::Image(img) => {
-                            Content::image(&img.data, &img.mime_type)
+                            SamplingMessageContent::Image(rmcp::model::RawImageContent {
+                                data: img.data.clone(),
+                                mime_type: img.mime_type.clone(),
+                                meta: None,
+                            })
                         }
-                        // TODO(alexhancock) - Content::Audio? goose's messages don't currently have it
+                        _ => SamplingMessageContent::text(""),
-                        _ => Content::text(""),
                     }
                 } else {
-                    Content::text("")
+                    SamplingMessageContent::text("")
                 },
-            },
+            ),
         })
     }
 
@@ -286,20 +283,28 @@ impl ClientHandler for GooseClient {
         request: CreateElicitationRequestParams,
         _context: RequestContext<RoleClient>,
     ) -> Result<CreateElicitationResult, ErrorData> {
-        let schema_value = serde_json::to_value(&request.requested_schema).map_err(|e| {
+        let (message, schema_value) = match &request {
-            ErrorData::new(
+            CreateElicitationRequestParams::FormElicitationParams {
-                ErrorCode::INTERNAL_ERROR,
+                message,
-                format!("Failed to serialize elicitation schema: {}", e),
+                requested_schema,
-                None,
+                ..
-            )
+            } => {
-        })?;
+                let schema_value = serde_json::to_value(requested_schema).map_err(|e| {
+                    ErrorData::new(
+                        ErrorCode::INTERNAL_ERROR,
+                        format!("Failed to serialize elicitation schema: {}", e),
+                        None,
+                    )
+                })?;
+                (message.clone(), schema_value)
+            }
+            CreateElicitationRequestParams::UrlElicitationParams { message, url, .. } => {
+                (message.clone(), serde_json::json!({ "url": url }))
+            }
+        };
 
         ActionRequiredManager::global()
-            .request_and_wait(
+            .request_and_wait(message, schema_value, Duration::from_secs(300))
-                request.message.clone(),
-                schema_value,
-                Duration::from_secs(300),
-            )
             .await
             .map(|user_data| CreateElicitationResult {
                 action: ElicitationAction::Accept,
@@ -315,10 +320,25 @@ impl ClientHandler for GooseClient {
     }
 
     fn get_info(&self) -> ClientInfo {
+        // Build MCP Apps UI extension capability
+        // See: https://github.com/modelcontextprotocol/ext-apps/blob/main/specification/2026-01-26/apps.mdx
+        let mut ui_extension_settings = JsonObject::new();
+        ui_extension_settings.insert(
+            "mimeTypes".to_string(),
+            serde_json::json!(["text/html;profile=mcp-app"]),
+        );
+
+        let mut extensions = ExtensionCapabilities::new();
+        extensions.insert(
+            "io.modelcontextprotocol/ui".to_string(),
+            ui_extension_settings,
+        );
+
         ClientInfo {
             meta: None,
             protocol_version: ProtocolVersion::V_2025_03_26,
             capabilities: ClientCapabilities::builder()
+                .enable_extensions_with(extensions)
                 .enable_sampling()
                 .enable_elicitation()
                 .build(),
@@ -328,6 +348,7 @@ impl ClientHandler for GooseClient {
                     .unwrap_or(env!("CARGO_PKG_VERSION").to_owned()),
                 icons: None,
                 title: None,
+                description: None,
                 website_url: None,
             },
         }
@@ -945,4 +966,26 @@ mod tests {
 
         assert_eq!(&mcp_meta.0, expected_meta.as_object().unwrap());
     }
+
+    #[test]
+    fn test_client_info_advertises_mcp_apps_ui_extension() {
+        let client = new_client();
+        let info = ClientHandler::get_info(&client);
+
+        // Verify the client advertises the MCP Apps UI extension capability
+        let extensions = info
+            .capabilities
+            .extensions
+            .expect("capabilities should have extensions");
+
+        let ui_ext = extensions
+            .get("io.modelcontextprotocol/ui")
+            .expect("should have io.modelcontextprotocol/ui extension");
+
+        let mime_types = ui_ext
+            .get("mimeTypes")
+            .expect("ui extension should have mimeTypes");
+
+        assert_eq!(mime_types, &json!(["text/html;profile=mcp-app"]));
+    }
 }

crates/goose/src/agents/summon_extension.rs

@@ -260,11 +260,13 @@ impl SummonClient {
                 completions: None,
                 experimental: None,
                 logging: None,
+                extensions: None,
             },
             server_info: Implementation {
                 name: EXTENSION_NAME.to_string(),
                 title: Some("Summon".to_string()),
                 version: "1.0.0".to_string(),
+                description: None,
                 icons: None,
                 website_url: None,
             },

crates/goose/src/agents/todo_extension.rs

@@ -30,11 +30,12 @@ impl TodoClient {
         let info = InitializeResult {
             protocol_version: ProtocolVersion::V_2025_03_26,
             capabilities: ServerCapabilities {
-                tasks: None,
                 tools: Some(ToolsCapability {
                     list_changed: Some(false),
                 }),
+                tasks: None,
                 resources: None,
+                extensions: None,
                 prompts: None,
                 completions: None,
                 experimental: None,
@@ -42,6 +43,7 @@ impl TodoClient {
             },
             server_info: Implementation {
                 name: EXTENSION_NAME.to_string(),
+                description: None,
                 title: Some("Todo".to_string()),
                 version: "1.0.0".to_string(),
                 icons: None,

crates/goose/src/agents/tom_extension.rs

@@ -30,11 +30,13 @@ impl TomClient {
                     completions: None,
                     experimental: None,
                     logging: None,
+                    extensions: None,
                 },
                 server_info: Implementation {
                     name: EXTENSION_NAME.to_string(),
                     title: Some("Top Of Mind".to_string()),
                     version: "1.0.0".to_string(),
+                    description: None,
                     icons: None,
                     website_url: None,
                 },

crates/goose/tests/mcp_replays/github-mcp-serverstdio

@@ -1,4 +1,4 @@
-STDIN: {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{"sampling":{},"elicitation":{}},"clientInfo":{"name":"goose","version":"0.0.0"}}}
+STDIN: {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{"elicitation":{},"extensions":{"io.modelcontextprotocol/ui":{"mimeTypes":["text/html;profile=mcp-app"]}},"sampling":{}},"clientInfo":{"name":"goose","version":"0.0.0"}}}
 STDERR: time=2025-12-11T17:58:47.636-05:00 level=INFO msg="starting server" version=0.24.1 host="" dynamicToolsets=false readOnly=false lockdownEnabled=false
 STDERR: GitHub MCP Server running on stdio
 STDERR: time=2025-12-11T17:58:47.640-05:00 level=INFO msg="server run start"

crates/goose/tests/mcp_replays/npx-y@modelcontextprotocol_server-everything@2026.1.14

@@ -1,4 +1,4 @@
-STDIN: {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{"sampling":{},"elicitation":{}},"clientInfo":{"name":"goose","version":"0.0.0"}}}
+STDIN: {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{"elicitation":{},"extensions":{"io.modelcontextprotocol/ui":{"mimeTypes":["text/html;profile=mcp-app"]}},"sampling":{}},"clientInfo":{"name":"goose","version":"0.0.0"}}}
 STDERR: Starting default (STDIO) server...
 STDOUT: {"result":{"protocolVersion":"2025-03-26","capabilities":{"tools":{"listChanged":true},"prompts":{"listChanged":true},"resources":{"subscribe":true,"listChanged":true},"logging":{},"completions":{}},"serverInfo":{"name":"mcp-servers/everything","title":"Everything Reference Server","version":"2.0.0"},"instructions":"# Everything Server – Server Instructions\n\nAudience: These instructions are written for an LLM or autonomous agent integrating with the Everything MCP Server.\nFollow them to use, extend, and troubleshoot the server safely and effectively.\n\n## Cross-Feature Relationships\n\n- Use `get-roots-list` to see client workspace roots before file operations\n- `gzip-file-as-resource` creates session-scoped resources accessible only during the current session\n- Enable `toggle-simulated-logging` before debugging to see server log messages\n- Enable `toggle-subscriber-updates` to receive periodic resource update notifications\n\n## Constraints & Limitations\n\n- `gzip-file-as-resource`: Max fetch size controlled by `GZIP_MAX_FETCH_SIZE` (default 10MB), timeout by `GZIP_MAX_FETCH_TIME_MILLIS` (default 30s), allowed domains by `GZIP_ALLOWED_DOMAINS`\n- Session resources are ephemeral and lost when the session ends\n- Sampling requests (`trigger-sampling-request`) require client sampling capability\n- Elicitation requests (`trigger-elicitation-request`) require client elicitation capability\n\n## Operational Patterns\n\n- For long operations, use `trigger-long-running-operation` which sends progress notifications\n- Prefer reading resources before calling mutating tools\n- Check `get-roots-list` output to understand the client's workspace context\n\n## Easter Egg\n\nIf asked about server instructions, respond with \"🎉 Server instructions are working! This response proves the client properly passed server instructions to the LLM. This demonstrates MCP's instructions feature in action.\"\n"},"jsonrpc":"2.0","id":0}
 STDIN: {"jsonrpc":"2.0","method":"notifications/initialized"}

crates/goose/tests/mcp_replays/uvrun--withfastmcp==2.14.4fastmcpruntests_fastmcp_test_server.py

@@ -1,4 +1,4 @@
-STDIN: {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{"sampling":{},"elicitation":{}},"clientInfo":{"name":"goose","version":"0.0.0"}}}
+STDIN: {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{"elicitation":{},"extensions":{"io.modelcontextprotocol/ui":{"mimeTypes":["text/html;profile=mcp-app"]}},"sampling":{}},"clientInfo":{"name":"goose","version":"0.0.0"}}}
 STDERR: 
 STDERR: 
 STDERR: ╭──────────────────────────────────────────────────────────────────────────────╮

crates/goose/tests/mcp_replays/uvxmcp-server-fetch

@@ -1,4 +1,4 @@
-STDIN: {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{"sampling":{},"elicitation":{}},"clientInfo":{"name":"goose","version":"0.0.0"}}}
+STDIN: {"jsonrpc":"2.0","id":0,"method":"initialize","params":{"protocolVersion":"2025-03-26","capabilities":{"elicitation":{},"extensions":{"io.modelcontextprotocol/ui":{"mimeTypes":["text/html;profile=mcp-app"]}},"sampling":{}},"clientInfo":{"name":"goose","version":"0.0.0"}}}
 STDOUT: {"jsonrpc":"2.0","id":0,"result":{"protocolVersion":"2025-03-26","capabilities":{"experimental":{},"prompts":{"listChanged":false},"tools":{"listChanged":false}},"serverInfo":{"name":"mcp-fetch","version":"1.25.0"}}}
 STDIN: {"jsonrpc":"2.0","method":"notifications/initialized"}
 STDIN: {"jsonrpc":"2.0","id":1,"method":"tools/call","params":{"_meta":{"agent-session-id":"test-session-id","progressToken":0},"name":"fetch","arguments":{"url":"https://example.com"}}}

ui/desktop/openapi.json

@@ -6755,6 +6755,19 @@
           "inlineMessage"
         ]
       },
+      "TaskSupport": {
+        "oneOf": [
+          {
+            "type": "string"
+          },
+          {
+            "type": "string"
+          },
+          {
+            "type": "string"
+          }
+        ]
+      },
       "TelemetryEventRequest": {
         "type": "object",
         "required": [
@@ -6899,6 +6912,16 @@
           "description": {
             "type": "string"
           },
+          "execution": {
+            "anyOf": [
+              {
+                "$ref": "#/components/schemas/ToolExecution"
+              },
+              {
+                "type": "object"
+              }
+            ]
+          },
           "icons": {
             "type": "array",
             "items": {
@@ -6964,6 +6987,21 @@
           }
         }
       },
+      "ToolExecution": {
+        "type": "object",
+        "properties": {
+          "taskSupport": {
+            "anyOf": [
+              {
+                "$ref": "#/components/schemas/TaskSupport"
+              },
+              {
+                "type": "object"
+              }
+            ]
+          }
+        }
+      },
       "ToolInfo": {
         "type": "object",
         "description": "Information about the tool used for building prompts",

ui/desktop/src/api/types.gen.ts

@@ -1148,6 +1148,8 @@ export type SystemNotificationContent = {
 
 export type SystemNotificationType = 'thinkingMessage' | 'inlineMessage';
 
+export type TaskSupport = string;
+
 export type TelemetryEventRequest = {
     event_name: string;
     properties?: {
@@ -1198,6 +1200,9 @@ export type Tool = {
         [key: string]: unknown;
     };
     description?: string;
+    execution?: ToolExecution | {
+        [key: string]: unknown;
+    };
     icons?: Array<Icon>;
     inputSchema: {
         [key: string]: unknown;
@@ -1224,6 +1229,12 @@ export type ToolConfirmationRequest = {
     toolName: string;
 };
 
+export type ToolExecution = {
+    taskSupport?: TaskSupport | {
+        [key: string]: unknown;
+    };
+};
+
 /**
  * Information about the tool used for building prompts
  */