Add option to truncate/limit build output size

[thomasttvo]

Problem

When using build_device session-set-defaults (and likely other build tools), the response contains the full xcodebuild output which can be ~14k+ tokens. This is expensive when using AI assistants that charge per token.

Claude Code shows this warning:

⚠ Large MCP response (~14.0k tokens), this can fill up context quickly

Proposed Solution

Add a configuration option to control output verbosity/size:

1. Environment variable like XCODEBUILDMCP_MAX_OUTPUT_LINES=100 or XCODEBUILDMCP_OUTPUT_VERBOSITY=minimal
2. Tool parameter like maxOutputLines or verbosity
3. Smart truncation - by default only return errors/warnings and last N lines of output, with option to get full output

Current Workaround

Using bash directly with output piping, but this loses the benefits of the MCP tool.

Thanks for the great tool!

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⚠️ Possible Duplicate Issue

• [Feature]: Filter build output for warnings and errors #68

🔗 Related PRs

#95 - Add XCODEBUILDMCP_ENABLED_WORKFLOWS environment variable for selective workflow loading [merged]
#147 - feat: Add suppressWarnings option to reduce context window usage [merged]

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[cameroncooke]

Thanks for the report — appreciate the detail. I just checked the current implementation: the build tools (e.g., build_device/build_sim) don’t return full xcodebuild stdout; they only surface warnings/errors and stderr plus a success/failure summary. If you’re seeing ~14k tokens in the MCP response, it may be coming from a different tool (or a specific code path/version).

Could you share exact repro steps and versions?

• Tool name(s) you called
• XcodeBuildMCP version
• Example invocation parameters
• Whether INCREMENTAL_BUILDS_ENABLED or suppressWarnings are set
• A trimmed sample of the response payload showing the large output

That will help confirm if this is a regression or a different tool emitting full logs.

[thomasttvo]

my apologies, I was mistaken, this issue came from session-set-defaults not build_device (edited the issue description), and adding suppressWarnings resolves it