coverage

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

With no annotations, the description carries the burden. It discloses that output is organized by tier and includes positive and negative coverage information, but it doesn't mention any operational details like response format, pagination, or data source limitations. This is adequate for a simple read tool but not rich.

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 tightly written sentences. The first lists key output categories, the second underscores the gap-reporting purpose. No filler.

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?

For a tool with no output schema and one optional filter, the description gives useful context but leaves open the output structure and the meaning of 'tier' and 'history_begins.' It is sufficient for basic understanding but not fully specified.

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 single parameter publisher is fully described in the schema as an optional publisher id. The description adds no additional semantics for how filtering works, so the baseline of 3 applies.

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 states the tool reports coverage information ('what we hold and what we lack, tier by tier') and enumerates specific output dimensions (counts, date ranges, history_begins, known gaps). It clearly distinguishes this from sibling tools focused on history, diffs, or searches, though it doesn't explicitly name an alternative.

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?

No guidance is provided on when to use this tool versus siblings like provenance or diff. The statement 'This tool exists to say what we do NOT have' implies a gap-analysis use case, but there are no explicit alternative references or preconditions.

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