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

Beyond the annotations (non-readOnly, non-idempotent, non-destructive), it discloses that the build undergoes validation on app id, version and device compatibility, that the validated build is returned, and that uploading alone does not start a run. The auth alternative is also behavioral context the annotations do not carry.

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?

Front-loaded with the action and the validation outcome, and each subsequent sentence carries routing or auth information. The phrasing 'The command from create_build_upload completes the upload itself' takes a moment to parse but is not wasted text.

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 two-parameter mutation with no output schema, the description covers inputs, validation behavior, the returned build, and the downstream run step. It does not say what happens when validation fails or what error/response shape to expect, which is the main remaining gap.

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 coverage is 100%, so the baseline is 3, but the description adds a real constraint: the parts array must contain EVERY part's etag, not a subset. The closing note about accepting a signed completeUrl instead of an API key adds auth context, though it is not tied to any schema field and is slightly ambiguous about how it is supplied.

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?

States a specific verb and resource — 'Finish the upload with every part's etag' — and adds that the build is validated (app id, version, device compatibility) and returned. It is clearly distinguishable from create_build_upload, which is named as the tool that produces the signed links.

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?

Gives explicit when-to-use routing: pass the returned build.id to run_test {buildId} or run_project {buildIds}. It also gives a when-not: the CLI command from create_build_upload already completes the upload, so call this only after uploading parts to the signed links yourself. An alternative auth path (signed completeUrl instead of an API key) is also stated.

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