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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 safety profile is covered. The description adds meaningful behavioral context — it's semantic coverage via call graph, and the blast-radius ranking is flagged as slower in the schema — but it doesn't describe output format or the openWorldHint implications. Baseline 3 is appropriate given annotation coverage.

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?

Two sentences, front-loaded with the core differentiator ('semantic coverage, not line coverage') followed by the optional ranking behavior. Every clause earns its place; no waste.

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?

Complete for a 2-param read-only analysis tool. The description explains the novel concept (call-graph-based semantic coverage), clarifies what the optional flag buys you, and the schema plus annotations cover the remaining requirements. Nothing needed for correct invocation is missing.

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 both parameters are already documented in the schema, including the default and slowdown note for weight_by_blast_radius. The description reinforces the intent of that flag ('so you know which missing tests are riskiest') but adds no syntax or format detail beyond the schema. Baseline 3 is correct when 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?

States a specific verb ('See which production functions are actually exercised') and resource (semantic coverage via call graph), and explicitly contrasts with a common alternative concept ('not line coverage'). No sibling tool covers test coverage, so the agent can identify its role immediately.

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 implies usage (assess coverage, prioritize missing tests) but offers no explicit when-to-use vs. when-not-to-use guidance, no prerequisites, and names no alternative sibling tool. A 3 is fair for implied but unstated routing.

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