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

Annotations are absent, so the description must carry all behavioral disclosure. It fully does so: it states the operation is free ('Free; no payment'), clarifies the output is an unsigned copy of the same report ('the same signed report ... unsigned'), covers transport behavior for hosted vs. local stdio, and lists all negative conditions when lookup fails ('Not found after the TTL, for previews, or for reports served by another process'). This is comprehensive and goes beyond what annotations usually provide.

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 three sentences that are dense but front‐loaded: the core purpose and TTL frame come first, followed by transport behavior, then disqualifiers. Each sentence adds a distinct piece of information. The middle parenthetical '(request_id re-attached, unsigned, as on the paid result)' is slightly convoluted but not wasted. It is concise relative to the amount of behavior it conveys.

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?

The tool has one parameter, no output schema, and no annotations. The description covers the main needs for correct invocation: what to provide, what you get back ('same bytes'), and when it fails. It does not mention response format or error messages, but for a re-fetch of an existing report, the output is already defined by the original report. The only plausible completeness gap is the absence of explicit note about whether the request_id must be within a signed session, but the TTL removal is already mentioned.

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 schema description already documents that request_id is 'the request_id from a paid citation_report / citation_report_large result' (100% coverage). The description adds the behavioral constraint 'within the cache TTL' and the requirement 'bought' that ties into the schema context. It does not re-explain the regex or format, which the schema covers. The extra semantics (recency and paid status) are useful and meet the baseline of 3 and exceed it slightly.

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?

Description opens with 'Re-fetch a paid report you already bought, by its request_id', which is a specific verb ('re-fetch'), resource ('a paid report'), and required scope ('you already bought'). It also distinguishes itself from siblings by the explicit exclusion 'for previews' and the paid/free contrast, so an agent can differentiate it from citation_report, citation_report_preview, and citation_report_large without opening a schema.

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?

Usage is clearly scoped to already-paid reports: 'Re-fetch a paid report you already bought.' The description also states when the tool is not to be used (beyond TTL, for previews, for reports served by another process). It does not name sibling tools by name (e.g., 'citation_report_preview') but the term 'previews' and the context of local stdio capability cover the alternatives. It could have explicitly said 'instead use ...' to earn a 5, but the guidance is otherwise explicit and accurate.

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