merge_pull_request

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

There are no annotations, so the description carries the transparency burden. It does disclose a useful non-obvious behavior: omitting merge_strategy uses the repository's configured default, falling back to merge_commit. However, it does not mention side effects such as whether the source branch gets closed, failure conditions for mergeable PRs, or whether the merge is reversible.

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?

A single front-loaded sentence conveys the core action and the most important parameter nuance in a parenthetical, with no filler. Every part of the description earns its place.

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?

The tool has no annotations and no output schema, and the description does not state return values, error/failure conditions, permissions, or side effects of merging. For a 5-parameter mutation tool, this leaves an agent without enough context to fully predict outcomes or handle failures.

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?

The schema covers repo_slug, pr_id, and message but leaves merge_strategy and close_source_branch underdocumented. The description adds meaningful semantics for merge_strategy by explaining the defaulting behavior when omitted, but it does not clarify close_source_branch or message beyond what the schema already provides, so it only partially compensates for the coverage gap.

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 ('Merge') and resource ('an open pull request'), which clearly distinguishes it from sibling PR lifecycle tools like update_pull_request, decline_pull_request, and approve_pull_request. An agent can immediately understand the core operation this tool performs.

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 states that the PR must be open but provides no guidance on when this tool is preferred over alternatives such as decline_pull_request or update_pull_request. No prerequisites or decision criteria are given; any usage direction is only implicit in the tool's name.

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