Index coverage and freshness

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

With no annotations, the description carries the full burden and excels: it explains auto-start behavior, non-blocking nature, and what counts/ranges are reported. It also hints that the first call may initiate a build, which is an important side effect for the agent to know.

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?

Three sentences, each packed with relevant information; no filler. It is front-loaded with the main output, followed by a use case and behavioral notes, making it highly efficient.

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 zero-parameter, no-output-schema tool, the description provides sufficient context on return values, use cases, and build behavior. It covers the essential information an agent needs to decide when and how to use it, including the distinction between no matches and unbuilt index.

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 tool has zero parameters, and schema coverage is trivially 100%. The baseline for 0 parameters is 4; the description adds no parameter info, but none is needed since the schema is empty.

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 reports index coverage, generation, and change counter, and specifically positions it as a diagnostic for empty search results. The verb 'Call this' and the resource (index status) distinguish it from sibling search tools like search and get_email.

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?

Provides explicit guidance to call when an empty search result needs differentiation between no matches and an unbuilt index, and advises polling to monitor build progress. It does not explicitly name alternatives, but the context implies when not to use (e.g., not for actual search results), so a 4 is warranted.

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