GitLab MCP Server

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

With no annotations provided, the description carries the full burden of behavioral disclosure but offers minimal information. It doesn't mention that this is a mutation operation (implied by 'Update'), what permissions are required, whether changes are reversible, or what the response contains. For a tool with 12 parameters that modifies merge requests, this lack of behavioral context is a significant gap.

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 extremely concise - a single sentence that communicates the essential constraint. There's no wasted language or unnecessary elaboration. It's front-loaded with the core requirement, though this brevity comes at the cost of completeness for other dimensions.

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 complex mutation tool with 12 parameters, no annotations, and no output schema, the description is inadequate. It doesn't explain what 'updating' entails, what fields can be modified, what happens when different parameter combinations are used, or what the tool returns. The agent would struggle to use this tool effectively without significant trial and error.

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 description adds minimal value beyond the input schema, which has 100% description coverage. It mentions that either mergeRequestIid or branchName must be provided, but this constraint isn't reflected in the schema's required fields (only project_id is required). The description doesn't explain parameter interactions, dependencies, or provide additional context about what fields are actually updatable.

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 verb ('Update') and resource ('merge request'), making the purpose immediately understandable. It distinguishes this tool from sibling tools like 'create_merge_request' by focusing on modification rather than creation. However, it doesn't specify what aspects can be updated beyond the identification requirement.

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 minimal guidance about when to use this tool, only stating that either mergeRequestIid or branchName must be provided. It doesn't explain when to choose this over alternatives like 'update_issue' for related work, or clarify prerequisites beyond the required project_id parameter. No explicit when-not-to-use guidance is present.

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