update_merge_request

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

The description goes beyond the openWorldHint annotation by explicitly stating it changes remote GitLab state, requires permissions, and returns validation/conflict/permission/rate-limit errors instead of silently ignoring invalid requests. This gives the agent a clear picture of side effects and error behavior.

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 four sentences with the core purpose front-loaded. It efficiently covers usage, behavior, and identifier handling, but the last sentence about pagination fields is slightly redundant given the schema and adds minor bloat.

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 tool with 14 parameters and no output schema, the description covers purpose, usage, side effects, and identifier semantics. It does not enumerate all updatable fields but those are already documented in the schema, so the high coverage lets the description focus on higher-level context. The 'branchName' inaccuracy is a minor gap.

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 a baseline of 3 is appropriate. The description adds guidance on providing project_id/group_id as numeric ID or URL-encoded path, but it introduces a misleading statement: 'mergeRequestIid or branchName required' conflicts with the schema which only requires project_id and has source_branch instead of branchName. This ambiguity reduces the score.

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 updates a merge request, distinguishing it from create and note tools. It names the specific resource and action, and explicitly differentiates from siblings by mentioning the corresponding create tool and note tool for other purposes.

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 explicit usage guidance: use for existing resources, choose create for new ones, and note tools for discussion-only text. It also implies that this tool is for updating MR attributes, not merging or approving, which clarifies when to use it vs. siblings like merge_merge_request or approve_merge_request.

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