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

Despite annotations already flagging destructive/openWorld, the description adds substantial context: exact price and network (Base), the free 402 challenge default, the owner-approval + approve_payment + signed signature prerequisites, no automatic retry, key-hygiene guidance, and an explicit caveat that evidence does not prove execution. That is richer behavioral disclosure than the annotations alone.

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?

Front-loaded with the core action and the cost/approval constraint, and every sentence carries information (price, approval, key safety, no retry, semantic limit). The compressed, clause-stacked style borders on telegraphic but wastes little.

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 costly, destructive, 5-parameter tool with no output schema, the description covers cost, prerequisites, retry behavior, and semantic scope. Gaps remain around the purpose of previous_attestation_digest and what a receipt actually contains, but the essentials for correct invocation are present.

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 only 20%, so the description must carry the load; it does explain digest, nonce, approve_payment, and payment_signature roles reasonably. But previous_attestation_digest is undocumented in both schema and description, and the 43-character base64url constraints are left to the pattern only.

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?

States a specific verb and resource — 'Witness a SHA-256 digest and fresh caller nonce at a time' — which is clearly distinct from hashing or verifying. It doesn't explicitly name how it differs from siblings like popcorn_hash or popcorn_verify, but the action is concrete enough to route on.

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?

Explains the payment flow (defaults to a free unpaid 402 challenge, then $0.001 USDC per receipt requiring approve_payment and a signed payment_signature) and warns 'No automatic retry'. However, it never states when an agent should choose this over popcorn_verify or popcorn_hash, and the free-vs-paid decision path is only implied.

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