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>

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
 ```