get_merge_request_approval_state

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

Annotations already declare readOnlyHint, and the description reinforces that with 'It is read-only'. Beyond annotations, it adds valuable behavioral detail: missing requests, unsupported GitLab versions, and permission failures are reported as errors. It also states the return type ('approval-state response'), which is useful given no output schema. This goes beyond what annotations provide, though it could specify the response structure more concretely.

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 three sentences: purpose, usage guidance with alternative, and behavioral/error notes. It is concise, front-loaded with the core purpose, and every sentence contributes meaningful information without redundancy.

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 read-only tool with two parameters and no output schema, the description covers purpose, usage context, error handling, and read-only nature. It is mostly complete, but the vague 'returns the approval-state response' leaves the exact shape of the response unspecified. Still, the given information supports correct invocation and decision-making, so it earns a 4.

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 input schema covers 100% of parameters with descriptions for both `project_id` and `merge_request_iid`. The description adds no additional meaning or usage hints for these parameters, so it provides no value beyond what the schema already offers. Baseline for high coverage is 3, and there is no extra contextual clarification.

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 clearly states the tool retrieves merge request approval details including approvers. It uses a specific verb 'Get' and resource, and distinguishes itself from the sibling `approve_merge_request` by noting it inspects rather than changes approval state. This makes the purpose unambiguous.

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 explicitly says to use this tool to inspect approval rules and approvers before deciding whether a merge request can be merged, and points to `approve_merge_request` as the alternative for changing state. This gives clear when-to-use and when-not-to-use guidance, directly addressing the decision context.

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