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

With no annotations, the description bears full responsibility for behavioral disclosure. It adds valuable context: it is 'Unmetered', returns data from the live census, and explicitly states 'No invented metrics' (ensuring data provenance). It also lists the exact output fields. While it omits error handling, caching, or authorization details, these are less critical for a read-only stats tool, making this robust transparency.

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 two efficient sentences. It front-loads the core purpose, then adds the unmetered note and the complete output field list, with no redundancy or filler. Every sentence contributes essential information.

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 simple tool with no parameters and no output schema, the description is fully complete. It states the source (live census), the API equivalence, and enumerates every returned field including a timestamp (captured_at). An agent can invoke it without ambiguity, and the output is fully anticipated.

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, so the description adds no parameter-specific meaning. Per the rubric, 0 params sets a baseline of 4. The schema coverage for parameters is trivially complete (no properties), so this score is appropriate without further description.

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 returns 'Ecosystem headline numbers from the live census' and enumerates the specific metrics (total servers, healthy/issues counts, popular, remote-capable, github-linked, captured_at). It also references the exact payload format (same as GET /v1/stats). This is specific and not a tautology, though it does not explicitly differentiate from sibling census tools (e.g., census_coverage, census_lookalikes) – the name and field list imply its distinct role.

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 this is the tool for quick summary stats by listing headline metrics and noting it is 'Unmetered', but it does not explicitly state when to use it vs siblings or provide exclusions (e.g., 'for detailed records, use census_lookup'). The guidance is understandable but left to inference.

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