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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile needs no restatement. The description adds genuinely new behavioral context that annotations cannot convey: the response deliberately surfaces 'explicit freshness unknowns', warning the agent that the manifest may report gaps or staleness rather than a clean snapshot. It says nothing about response shape, but an output schema exists to cover that.

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?

It is only two sentences and wastes nothing, but the first is a telegraphic noun-phrase fragment that reads like a field list rather than a statement, and the interpretive clause 'explicit freshness unknowns' lands last and is the least self-explanatory part. The most important directive, 'Check before research', is buried at the end rather than front-loaded.

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 read-only metadata tool with full annotation coverage and an output schema, the description supplies the missing pieces: what dimensions of coverage are reported and the recommended call ordering. Only the meaning of 'freshness unknowns' remains slightly opaque, which keeps it from a 5.

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, so there is no parameter semantics to explain and the baseline of 4 applies. The description correctly does not waste space describing inputs and instead spends its words on what the corpus state means.

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 names the concrete payload: loaded counts, snapshot years, deployment identity, and freshness unknowns, which tells an agent this is a corpus-coverage/metadata inspector rather than a search or fetch tool like every sibling. It stops short of a verb-led statement such as 'returns' and relies on the title to supply 'Inspect', so it is clear but not maximally explicit.

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?

'Check before research' is a direct, actionable when-to-use instruction: call this before issuing search or citation queries to know what the corpus actually covers. It gives no when-not-to-use condition and never names which sibling queries it should precede, but the trigger context is unambiguous for a zero-parameter tool.

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