MR Diffs

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 agent knows this is a safe, repeatable read operation. The description adds minimal behavioral context beyond annotations—it mentions what data is returned ('diff statistics... per-file additions/deletions and diff refs') but doesn't cover rate limits, authentication needs (though schema hints at optional credentials), or response format. With annotations covering safety, a 3 is appropriate for adding some value.

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 with zero waste. It's front-loaded with the core purpose and includes specific details ('per-file additions/deletions and diff refs') without redundancy. Every word earns its place.

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 moderate complexity (read-only diff statistics), rich annotations (safety profile covered), and 100% schema coverage, the description is adequate but has gaps. It lacks output details (no output schema), doesn't explain authentication behavior (optional credentials), and provides no usage guidelines. It's minimally viable but not fully complete for optimal agent use.

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%, with clear documentation for all three parameters (projectPath, iid, userCredentials). The description doesn't add any parameter-specific semantics beyond what the schema provides—it doesn't explain parameter relationships, formats beyond schema hints, or usage examples. Baseline 3 is correct when schema does the heavy lifting.

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's purpose: 'Get diff statistics for a merge request, including per-file additions/deletions and diff refs.' It specifies the verb ('Get'), resource ('diff statistics for a merge request'), and scope ('per-file additions/deletions and diff refs'). However, it doesn't explicitly differentiate from sibling tools like 'get_merge_request_commits' or 'get_merge_requests', which reduces clarity slightly.

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 no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites (e.g., needing an existing merge request), exclusions, or comparisons to similar tools like 'get_merge_request_commits' (which might provide commit-level vs. diff-level data). Usage is implied but not explicitly stated.

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