feat: make tool output size limit configurable via GOOSE_MAX_TOOL_RESPONSE_SIZE (#9256)

Signed-off-by: Douwe Osinga <douwe@squareup.com>
Co-authored-by: Douwe Osinga <douwe@squareup.com>

crates/goose/src/agents/large_response_handler.rs

@@ -1,14 +1,22 @@
+use crate::config::Config;
 use chrono::Utc;
 use rmcp::model::{CallToolResult, Content, ErrorData};
 use std::fs::File;
 use std::io::Write;
 
-const LARGE_TEXT_THRESHOLD: usize = 200_000;
+const DEFAULT_LARGE_TEXT_THRESHOLD: usize = 200_000;
+
+fn large_text_threshold() -> usize {
+    Config::global()
+        .get_param::<usize>("GOOSE_MAX_TOOL_RESPONSE_SIZE")
+        .unwrap_or(DEFAULT_LARGE_TEXT_THRESHOLD)
+}
 
 /// Process tool response and handle large text content
 pub fn process_tool_response(
     response: Result<CallToolResult, ErrorData>,
 ) -> Result<CallToolResult, ErrorData> {
+    let threshold = large_text_threshold();
     match response {
         Ok(mut result) => {
             let mut processed_contents = Vec::new();
@@ -17,7 +25,7 @@ pub fn process_tool_response(
                 match content.as_text() {
                     Some(text_content) => {
                         // Check if text exceeds threshold
-                        if text_content.text.chars().count() > LARGE_TEXT_THRESHOLD {
+                        if text_content.text.chars().count() > threshold {
                             // Write to temp file
                             match write_large_text_to_file(&text_content.text) {
                                 Ok(file_path) => {
@@ -107,7 +115,7 @@ mod tests {
     #[test]
     fn test_large_text_response_redirected_to_file() {
         // Create a text larger than the threshold
-        let large_text = "a".repeat(LARGE_TEXT_THRESHOLD + 1000);
+        let large_text = "a".repeat(DEFAULT_LARGE_TEXT_THRESHOLD + 1000);
         let content = Content::text(large_text.clone());
 
         let response = Ok(CallToolResult::success(vec![content]));
@@ -166,7 +174,7 @@ mod tests {
     fn test_mixed_content_handled_correctly() {
         // Create a response with mixed content types
         let small_text = Content::text("Small text");
-        let large_text = Content::text("a".repeat(LARGE_TEXT_THRESHOLD + 1000));
+        let large_text = Content::text("a".repeat(DEFAULT_LARGE_TEXT_THRESHOLD + 1000));
         let image = Content::image("image_data".to_string(), "image/jpeg".to_string());
 
         let response = Ok(CallToolResult::success(vec![small_text, large_text, image]));

documentation/docs/guides/environment-variables.md

@@ -364,6 +364,7 @@ These variables control how goose handles [tool execution](/docs/guides/managing
 | `GOOSE_CLI_TOOL_PARAMS_TRUNCATION_MAX_LENGTH` | Maximum length for tool parameter values before truncation in CLI output (not in debug mode) | Integer | 40 |
 | `GOOSE_DEBUG` | Enables debug mode to show full tool parameters without truncation. Can also be toggled during a session using the `/r` [slash command](/docs/guides/goose-cli-commands#slash-commands) | "1", "true" (case-insensitive) to enable | false |
 | `GOOSE_SEARCH_PATHS` | Prepends additional directories to PATH for extension commands | JSON array of paths (for example, `["/usr/local/bin", "~/custom/bin"]`) | System PATH only |
+| `GOOSE_MAX_TOOL_RESPONSE_SIZE` | Maximum character count for a single tool response before it is written to a temporary file instead of being included inline in the conversation | Positive integer (e.g., 100000, 200000) | 200000 |
 | `GOOSE_SHELL` | Overrides the shell used for Developer extension shell commands | Shell executable path or name (for example, `/bin/zsh`, `pwsh`, `C:\cygwin64\bin\bash.exe`) | Unix: `/bin/bash` if present, otherwise `$SHELL`, otherwise `sh`. Windows: `cmd` |
 
 **Examples**
@@ -379,6 +380,9 @@ export GOOSE_CLI_TOOL_PARAMS_MAX_LENGTH=100  # Show up to 100 characters for too
 # Add custom tool directories for extensions
 export GOOSE_SEARCH_PATHS='["/usr/local/bin", "~/custom/tools", "/opt/homebrew/bin"]'
 
+# Lower the tool response size limit for smaller-context models
+export GOOSE_MAX_TOOL_RESPONSE_SIZE=100000
+
 # Use zsh for Developer extension shell commands
 export GOOSE_SHELL=/bin/zsh
 ```