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

With no annotations available, the description carries the full burden and does so well. It discloses fetching over plain HTTPS, checking for quoted text, not browsing the web, marking unverifiable items as 'unverified — sandbox stub', and signing deliverables with Ed25519. It also sets expectations for testnet semantics and free sandbox usage, which helps an agent judge output trustworthiness.

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 front-loaded with the core action, and each subsequent sentence adds non-redundant constraints: HTTPS fetching, no web browsing, stub fallback, and sandbox/testnet behavior. It is compact despite covering operational and trust-related details.

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 tool with no output schema, the description covers the main return signals: HTTP status, quoted-text presence, and 'unverified — sandbox stub'. It does not specify the exact response structure or error formatting, but the information provided is sufficient for an agent to invoke the tool correctly and interpret basic results.

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 50% because `input` has no schema-level description. The prose maps claims, sources, and quoted_text to the verification behavior, which adds useful meaning. However, the description never explains the relationship between `input` and `quote_id` or that they represent alternative submission flows; that important context is left entirely to the quote_id schema 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 states a precise action: 'Check factual claims against their cited sources,' and details the exact mechanism—fetching each source URL over HTTPS, reporting HTTP status, and checking whether quoted text appears. It clearly sets a boundary by saying it does NOT browse the open web or perform independent research. It does not explicitly distinguish itself from siblings such as citation_audit, so it stops one step short of a 5.

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 makes the operating context clear: the tool only verifies claims against user-supplied source URLs and is not appropriate for open-ended research. The 'when not' guidance is explicit, but no alternative tool is named, so it lacks the full when/alternative guidance needed for a 5.

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