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

Annotations already establish that this is a read-only, idempotent, non-destructive call, so the safety profile is covered. The description adds real value by enumerating the receipt's contents (sub-claims, sources, per-family verdicts with validated verbatim quotes, coherence, verdict, payment) and by noting that only a paid check yields a receipt, which is behavior the annotations cannot convey.

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?

A single front-loaded sentence: the action and resource come first, the parenthetical expands the return payload, and nothing is wasted. Its length is proportionate to a one-parameter lookup tool.

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?

Because there is no output schema, the description correctly shouldered the burden of describing return contents, and it does so well. The remaining gap is minor but real: it does not say what happens if the check is unpaid or the receipt_id is unknown (error versus empty), which matters for an openWorldHint 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?

With only one parameter and 100% schema description coverage, the schema already carries the semantics, including the constraint range and the cg_..._........ example format. The description restates that receipt_id identifies a sealed record but adds no format, origin, or error-handling detail beyond the schema — baseline 3.

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 definition uses a specific verb and resource ("Fetch a stored ClaimGate receipt") and immediately qualifies the artifact ("the sealed record of a paid fact check"), so the agent knows exactly what comes back. It does not, however, distinguish itself from the fact_check_status sibling, even though the two could be confused when a user wants the current state of a check versus the sealed receipt.

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 requirement to hold a receipt_id (implicitly returned only after a paid fact check completes) suggests when the tool is applicable, but usage is only implied. There is no explicit statement such as "call after fact_check_claim completes" or "use fact_check_status while the check is still running," which would have removed the guesswork among four siblings.

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