get_coverage_gaps

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. It reveals the underlying methodology (import-graph reachability from test files), which is a meaningful behavioral trait beyond the tool name. It implies a read-only analysis, though it doesn't discuss edge cases like dynamic imports, but that's acceptable for this simple tool.

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 exactly two sentences, with the core behavior in the first sentence and a usage prompt in the second. There is no wasted wording, and the information is front-loaded.

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, the description sufficiently explains what it does and when to use it. All parameters are documented in the schema, so the only missing piece is the return format (e.g., whether it returns file paths, a count, or a structure), since there is no output schema. This is a minor gap and doesn't block correct invocation.

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 input schema already provides 100% description coverage for all three parameters (project_root, limit, source_dirs). The tool description adds no additional parameter-level semantics, so the baseline of 3 is appropriate because 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 uses a specific verb ('Finds') and resource ('source files not reachable from any test file through the import graph'), clearly defining its scope as completely untested code. This distinguishes it from sibling tools like get_dependency_graph or identify_unreachable_modules, which target different concepts of unreachability.

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 explicitly gives a use-case question ('which parts of the codebase have zero test coverage?'), telling the agent when to invoke it. It does not explicitly list exclusions or name alternative tools, but the context is clear enough for selection.

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