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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds that the tool requires a project ID and returns specific fields, but return fields are also in the output schema, so this adds limited value. No hidden behaviors are disclosed, but annotations carry the burden.

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 only two sentences and front-loads the core purpose, which is structurally concise. However, the inaccuracy about filtering by author means the second sentence does not fully earn its place. A concise, accurate description would score higher.

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?

Given the tool's simplicity, full schema coverage, and output schema existence, the description is mostly adequate. The author filter claim introduces ambiguity and the default state (opened) is not mentioned, though it is in the schema. The description is not fully complete due to the inaccuracy.

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 is 3. However, the description claims 'Filter by state and author', but the schema does not include an 'author' parameter. This is misleading and could cause an agent to pass an unsupported parameter. The error in the description outweighs the schema's completeness, so a lower score is warranted.

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 ('List') and identifies the exact resource ('merge requests in a GitLab project by project ID'). It clearly differentiates from sibling tools like gitlab_list_issues and gitlab_list_projects by specifying merge requests and the project scoping. The return fields are also listed, aiding purpose clarity.

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 provides clear context: use this tool to list merge requests for a given project ID. It does not explicitly mention alternatives or exclusions, but the sibling tools are for different resources (files, projects, issues), so the intended usage is unambiguous. A slightly higher score would require explicit when-not guidance.

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