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

With no annotations, the description carries the full burden. It usefully discloses that the org's agent-writes switch is required and that merging is treated as a destructive action subject to review, with a person's approval by default. It does not describe merge method behavior, branch cleanup, irreversibility, or what the response contains, so meaningful behavioral gaps remain.

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 short, front-loaded with the action, and then moves immediately to the prerequisite and approval constraints. Every sentence earns its place and there is no redundant restatement of the schema.

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?

An output schema exists, so return values do not need to be explained. The input schema fully documents both parameters, and the description adds the key authorization and approval context for a mutation tool. It is reasonably complete for calling the tool, though merge-specific behavioral details are absent.

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%, so both parameters are fully documented in the input schema. The description adds no parameter-level meaning beyond the schema and does not mention the PR number or repository binding context. Baseline 3 applies because the schema does the heavy lifting.

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 uses a specific verb and resource: 'Merge a pull request.' This is clearly distinct from siblings like github_close, github_open_pr, or review_decide. However, it does not explicitly name any sibling or explain how it differs from adjacent operations such as closing or approving a PR.

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 gives clear prerequisite context: the org's agent-writes switch must be enabled, and approval follows the org's review settings for destructive actions. It does not explicitly say when not to use this tool or name alternatives, but the operational context is strong enough for an agent to know this is a gated merge action.

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