Attach build to version

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

Annotations already declare readOnlyHint=false and idempotentHint=true; the description adds the key non-obvious behavior that an existing attached build is replaced, plus the validity/same-app/same-platform constraints. It stays consistent with the annotations (replacing an attachment is not data destruction, and re-attaching is idempotent) but does not describe failure modes or the response.

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 sentences, no filler, and the replacement behavior is stated up front before the validity constraint. Every clause carries information the agent needs.

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 the action, the overwrite behavior, and the preconditions an agent must verify first. What is missing is only what happens on an invalid or mismatched build (error vs silent no-op).

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% and both parameters carry their own descriptions with provenance hints (from list_builds, from list_app_store_versions). The description adds conceptual context (build/version pairing) but no format or edge-case detail beyond the schema, 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?

States a specific verb and resource ('Attaches a processed build to an App Store version') and immediately names the replacement semantics. It is clearly distinct from siblings like add_build_to_beta_groups and list_builds, which handle beta distribution and enumeration rather than version attachment.

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 real preconditions: the build must be VALID and belong to the same app and platform, which tells the agent when this call will succeed. It does not explicitly route to alternatives (e.g. beta-group attachment via add_build_to_beta_groups), so it stops short of full when/when-not guidance.

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