Update GitLab merge request

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

Annotations already provide readOnlyHint=false, destructiveHint=false, and idempotentHint=false. The description adds that it can toggle draft/ready and open/closed state, which is useful behavioral context. However, it does not disclose potential side effects (e.g., removing source branch, locking discussion) or prerequisites, so it only partially goes beyond annotations.

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 a single, efficient sentence that front-loads the action and enumerates key update categories. Every word contributes value, with no fluff or 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?

Although an output schema exists, making return-value documentation unnecessary, the description is too brief for such a complex tool. It lacks parameter interplay, edge cases, and behavioral caveats, and the low schema coverage means many parameters remain unexplained. This is a minimal but not complete description.

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 only 12%, so the description must compensate for the many undocumented parameters. It mentions several update categories (metadata, branches, assignees, reviewers, labels, draft/ready, open/closed) but omits parameters like squash, milestone_id, discussion_locked, allow_collaboration, and does not clarify the relationship between labels, add_labels, and remove_labels. This is insufficient for a 17-parameter tool.

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 an existing merge request and lists the editable aspects (metadata, branches, assignees, reviewers, labels, draft/ready, open/closed). This differentiates it from sibling tools like create_merge_request or merge_merge_request, though it doesn't explicitly name alternatives.

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?

No guidance is provided on when to use this tool versus alternatives. It does not state 'use for modifying existing MRs' or contrast with merge_merge_request, rebase_merge_request, or create_merge_request. The usage context is only implied by the verb 'update'.

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