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

Annotations already establish read-only, idempotent, non-destructive behavior. The description adds value by exposing the two return shapes: evidenced Gap[] with a chain, and no_evidence_available with a reason. It does not discuss auth or failure modes, but it gives meaningful behavioral context beyond the annotations.

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 core sentence is front-loaded and the return union is useful, but the duplicate 'Returns' statement and the placeholder example add little information. It is compact overall, but not every sentence 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?

There is no output schema, so the description's return union is necessary and helpful. However, it does not explain what a Gap contains, what 'chain' means, or what the optional 'repo' parameter does. Good enough for basic invocation, but incomplete for a sophisticated agent.

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 0%, so the description must carry parameter meaning. It clarifies scope_kind choices and the conditional scope_id requirement, which helps, but the 'repo' parameter remains unexplained. Partial compensation for a low-coverage schema.

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 gives a specific action ('Enumerate structural coverage gaps') and clarifies what counts as a gap with examples: silent tools, artifacts with no eval, and un-probed tenants. It is clear enough to distinguish the tool's function from general introspection siblings, though it does not explicitly compare itself to any sibling.

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 explains the scoping rules: scope_kind is needed and scope_id is required for tenant scope. This is useful invocation guidance, but the description never explicitly states when to choose this tool over related introspection/probe tools or when it should not be used.

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