build_run

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

Without annotations, the description must carry the transparency burden. It discloses that instrumentation is always enabled, which is a key behavioral trait, and mentions structured error/warning output and a buildId. However, it omits potential side effects (e.g., DerivedData creation, system modifications) and does not explain failure modes, so it is only partially transparent.

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 a single sentence that packs all key information: the action, the always-on instrumentation, the structured output, and the buildId for later reporting. There is zero waste or redundancy, making it appropriately concise and front-loaded.

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?

While the description gives a solid high-level overview, it lacks details on the expected output structure (no output schema), parameter formatting for the undocumented fields, and any prerequsites or side-effect caveats. For a build tool with 5 parameters, it is adequate but leaves notable gaps in fully guiding an agent.

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 low (40%): only deep and projectPath have descriptions, while scheme, destination, and configuration are undocumented. The tool description does not compensate for these missing semantics; it only mentions instrumentation generally without linking to specific parameters. This leaves the agent guessing about accepted values for three out of five parameters.

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 'Run an Xcode build' and distinguishes this tool by noting build-timing instrumentation is always enabled, returning structured errors/warnings and a buildId for build_timing_report. This differentiates it from sibling tools like cache_inspect and build_timing_report.

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 provides clear context: this is the tool to use when you want to run a build with timing instrumentation and obtain a buildId for later reporting. It does not explicitly mention alternatives or when-not-to-use, but the specific mention of instrumentation and buildId implies the intended usage scenario.

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