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

Annotations already establish readOnly, idempotent, non-destructive, closed-world behavior, so the description doesn't need to restate safety. It adds real value by disclosing the shape of the report (four distinct metrics, including a staleness comparison against the published archive) and by explaining how to interpret an empty search result. It says nothing about cost, latency, or whether the numbers are cached, which keeps it below a 5.

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 primary metric list, and each clause maps to a distinct returned number rather than padding. The first sentence is long and runs four items together, which costs a little readability but not substance.

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?

With no parameters and no output schema, the description carries the burden of explaining what comes back, and it does so by naming the four reported measures plus the freshness comparison. Exact field names and units are unspecified, but an agent has enough to decide to call it and to interpret the result.

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 takes zero parameters and schema coverage is 100%, so per the rubric the baseline is 4. There is nothing for the description to disambiguate, and it correctly implies a single parameterless call.

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 uses a specific verb ("Reports") and enumerates four concrete facets of the resource: searchable document count, text volume covered, per-filter archive visibility, and index-vs-published-archive freshness. No sibling tool (search, fetch, get_document, list_collections) produces coverage or freshness metadata, so the purpose is unambiguous even without naming 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?

"Use for questions about what the archive covers or how current it is" gives clear positive conditions, and "or to judge how much an empty search result means" supplies a non-obvious secondary use case tied to sibling tools. It stops short of stating when not to call it (e.g., that it is not a substitute for search), so it misses the explicit-exclusion bar for a 5.

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