Gaffer 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 and does well by disclosing key behaviors: it explains the sorting order (lowest coverage first), filtering logic (below threshold), return format (list with metrics), and important caveats about result dominance by file types. It also mentions API key requirements and projectId necessity. It doesn't cover rate limits or auth details beyond the API key note.

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 well-structured with clear sections (purpose, returns, usage notes, parameters, important caveats, prioritization advice). It's appropriately sized but could be slightly more concise by integrating the parameter details more seamlessly rather than listing them separately after already being in the schema.

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 complexity (filtered analysis with sorting), no annotations, but with a rich input schema (100% coverage) and output schema (implied by 'Returns' section), the description is complete. It covers purpose, usage, behavioral context, parameters, returns, caveats, and sibling differentiation, providing all necessary context for effective 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%, so the schema already documents all parameters thoroughly. The description repeats parameter information in the 'Parameters' section but adds minimal extra semantics beyond what's in the schema (e.g., context for maxCoverage default as 'untested'). Baseline 3 is appropriate since the 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 files with little or no test coverage' with specific details about sorting (by coverage percentage, lowest first) and filtering (below a threshold). It distinguishes from siblings like 'get_coverage_for_file' by emphasizing broad analysis vs. targeted path analysis.

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 guidance on when to use this tool vs. alternatives: it specifies to use 'list_projects' first to find project IDs, warns that results may be dominated by certain file types, and recommends using 'get_coverage_for_file' for targeted analysis of specific code areas. It also includes prerequisites for API key usage.

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