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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=true), so the description is free to add what they cannot: that it "Walks the Merkle path itself, so the answer does not rest on Rotten America's word." That discloses the verification method and trust model, which materially changes how an agent should present the result. It stops short of a 5 by not stating failure behavior (what happens if the hash is unknown or the proof does not resolve).

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?

Three sentences, front-loaded with the claim and its method before the privacy constraint. Every sentence carries unique information: capability, trust model, and access precondition. Nothing is repeated from the title or annotations.

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?

There is no output schema, so the description carries some burden for describing the result, and it only implies the outcome ("proves... is on the ledger and in Bitcoin") without saying what a positive, negative, or pending verification returns. Given the tool is a simple two-parameter read, everything needed to invoke it correctly is present; only the response shape is under-specified.

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%, and both parameters carry their own descriptions including the slug's source and the 64-hex pattern. The description's mention of "the signer's receipt" and "64 hex characters" restates rather than extends the schema, so the baseline 3 applies.

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?

Uses a specific verb ("Proves") plus a precise resource ("one signature is on a petition's public ledger and in Bitcoin") and names the input that scopes it ("the signature hash on the signer's receipt"). This is unmistakably distinct from the siblings find_petitions and get_petition, which retrieve rather than verify.

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?

States the triggering condition clearly (you have the 64-hex receipt hash) and adds a hard exclusion: "Only the signer has their receipt hash; never ask for or guess anyone's personal details." It does not explicitly route to a sibling (e.g., "to view petition details use get_petition"), so it falls short of a 5, but the when/when-not framing is explicit enough to select the tool confidently.

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