approve_merge_request

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

The annotation openWorldHint: true is non-standard and gives the agent little safety information, so the description carries the full burden for this state-changing operation. It discloses that review state is mutated, that auth/permission may be required, and that either an updated result or a permission/state error is returned — meaningful behavioral context beyond the generic annotation. Slight deduction for not addressing idempotency or double-approval behavior, but this is well above the minimum viable bar.

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?

Three sentences, each earning their place: the first states the core action, the second handles scope and sibling differentiation, and the third covers side effects, permissions, and return behavior. Front-loaded and free of redundancy. This is textbook economical writing.

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 moderate-complexity mutation with 4 documented parameters and no output schema, the description discloses the critical operational aspects: what it doesn't do, what state it changes, what permissions matter, and what the caller can expect in return. The lack of an output schema raises the burden, and the description meets it by noting the return value. Could have added error taxonomy (e.g., not-found vs. already-approved cases), but nothing essential 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 schema already documents all four parameters (project_id, merge_request_iid, sha, approval_password). The description makes a passing connection to the permission semantics of the approval_password parameter, but adds no genuinely new parameter-level information. Baseline of 3 is correct since 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?

Uses a specific verb and resource ('record an approval on an existing merge request') and explicitly declares what it does NOT do ('does not merge the request or change its source branch'). This directly differentiates it from the sibling merge_merge_request, letting an agent route correctly without opening either 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?

Provides clear context on when this is appropriate by contrasting with merging, and warns about preconditions ('may require re-authentication or approval permission'). It stops short of naming the exact sibling (merge_merge_request) to delegate to, so the alternative is implied rather than explicit.

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