Merge a pull request

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

Annotations already flag destructiveHint=true and idempotentHint=true, but the description adds substantial context beyond them: the forge refuses non-mergeable PRs (conflicts, failing required checks, missing approvals) and reports why, delete_branch mutates the head branch afterwards, and the response is returned in get_pull_request's shape. That is exactly the side-effect and failure-mode detail an agent needs on a destructive tool.

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?

Densely packed but front-loaded: the write-mode condition and style enumeration come first, then guard rails, then failure modes, then return shape. Every clause carries distinct information; no filler.

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 destructive, 8-parameter mutation tool with no output schema, the description covers the precondition, side effects, refusal reasons, and return value shape. Nothing an agent needs to invoke it correctly is missing.

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 would be 3; the description earns more by explaining that style availability depends on repository settings, that head_sha must be the full SHA from get_pull_request, and that absent title causes the forge to compose one. These clarify the interaction between parameters rather than restating their types.

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+resource (merge a pull request) with the exact identifier triplet (owner/repo/index) and the write-mode precondition. An agent can distinguish it from get_pull_request or create_pull_request_review without opening the 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?

Explicitly covers the precondition (requires write mode) and the conditional-merge pattern ('Pass head_sha ... to merge only if nothing was pushed since you looked'). It also enumerates conditions under which the operation will be refused. It stops short of naming an alternative sibling when merge is unavailable, so a 4 rather than a 5.

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