Add build to TestFlight groups

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

The annotations already declare the mutation profile: not read-only, idempotent, non-destructive, and open-world. The description adds a genuinely useful behavioral gate that the annotations cannot express: external groups are withheld until beta app review passes. It does not describe what a repeat call returns or what happens on partial group failures, so it falls short of 5.

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?

Two short sentences, with the core action front-loaded and the conditional caveat second. There is no filler or restatement of the title.

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 linking tool with a full schema, complete annotations, and no output schema, the description covers the operational caveat an agent most needs. It omits only secondary details such as the response shape or behavior when a build is already assigned, which the idempotentHint partially covers.

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%, and the schema itself documents buildId as coming from list_builds and betaGroupIds as coming from list_beta_groups. The description contributes no additional parameter semantics, so the baseline 3 applies.

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 gives a specific verb and resource: makes a build available to TestFlight beta groups. That is distinguishable from list_beta_groups, invite_beta_tester, and submit_build_for_beta_review without opening any schema.

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?

It states a clear precondition — external groups receive the build only after beta app review — and explicitly points to submit_build_for_beta_review as the prerequisite tool. It stops short of saying when to choose this over adjacent actions (for example, inviting testers or setting test notes), so it is not a full when/when-not treatment.

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