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

Annotations already cover the safety profile (readOnlyHint, idempotentHint, openWorldHint), and the description adds substantially beyond them: the exact verdict vocabulary returned, that results are cited with an as-of date, and that an Ed25519-signed receipt covering question/verdict/sources/time is verifiable offline against a published key. That is real, auditable behavioral context.

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 core action and return values are front-loaded in the first two sentences, which earns its place. The receipt sentence is long and slightly promotional, and 'Not advice' is a thin fragment, but overall the text is reasonably tight for the amount of information conveyed.

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 output schema, the description carries the burden of describing returns and does so by naming all four verdicts and the citation/as-of-date framing. It also covers auditability and where the signing key lives, so an agent has what it needs to call and interpret the tool.

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?

Schema coverage is 100%, so both parameters and the routing role of series_id are already fully documented in the schema. The description implies the claim must be a dated figure and enumerates return verdicts, but adds no syntax or usage detail for the parameters themselves, so it lands at the baseline.

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 a specific action (submit a dated figure claim for verification) and its outcome (a verdict of verified/stale/contradicted/unknown cited to the publisher's own series). It is clear on its own, but it never names or distinguishes itself from siblings like check_document, check_entity, or verify_citation, so an agent must infer the boundary from the name alone.

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?

'Relevant wherever a number is going onto a page, deck or decision' gives concrete when-to-use context, and the schema notes series_id bypasses the router when routing was ambiguous. However, there is no explicit when-not guidance or routing to any named alternative among the check_*/verify_* siblings.

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