XcodeBuildMCP

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden. It discloses key behavioral traits: it runs tests using xcodebuild test, parses xcresult output, and works on physical devices. However, it doesn't mention performance characteristics, error handling, side effects, or what the output looks like (no output schema). The 'IMPORTANT' note about required parameters is helpful but basic.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is appropriately sized and front-loaded with the core purpose in the first sentence. The second sentence highlights required parameters with 'IMPORTANT', which is useful. However, the device list in parentheses could be slightly verbose, and the structure could be more streamlined.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a tool with 8 parameters, no annotations, and no output schema, the description provides adequate but incomplete context. It covers the what (runs tests on physical devices) and key requirements, but lacks details on output format, error conditions, performance implications, or how it differs behaviorally from similar tools. Given the complexity, it should do more to compensate for missing structured data.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all 8 parameters thoroughly. The description adds minimal value beyond the schema by emphasizing that projectPath, scheme, and deviceId are required, but doesn't provide additional semantic context like parameter interactions or usage examples. Baseline 3 is appropriate when schema does the heavy lifting.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose with specific verbs ('Runs tests', 'parses xcresult output') and resources ('Apple project', 'physical device'). It explicitly distinguishes from sibling tools by specifying it's for physical devices (not simulators) and uses xcodebuild test, unlike other test tools like test_sim_id_proj or test_macos_proj.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage context by specifying 'physical device' and mentioning required parameters, but doesn't explicitly state when to use this tool versus alternatives like test_sim_id_proj or test_device_ws. It mentions deviceId must be 'obtained from list_devices' (in schema), providing some prerequisite guidance, but lacks clear when/when-not directives.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.