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

With no annotations, the description carries the full burden, and it does disclose two behavioral facts: verification is free and requires no API key. However it omits the return semantics (does it return a boolean, a validity verdict, or the decoded payload?) and any failure modes for malformed receipts, which matters for a tool with no output schema.

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?

Two terse fragments with zero padding, front-loading the action and the algorithm. It is efficient, though the brevity borders on under-specification rather than elegant concision.

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 annotations, no output schema, and an undocumented nested object parameter, the description should explain the expected receipt shape and the verdict format. Neither is present, so an agent knows the intent but not how to call it correctly.

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 single 'receipt' parameter is a nested object with 0% schema description coverage, and the description only hints that it carries an Ed25519 signature. It gives no detail on the object's expected fields (payload, signature, key id, encoding), so the agent must guess the shape.

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 (check) and resource (PazAIr receipt signature) plus the signature scheme (Ed25519), which distinguishes it from the generic sibling 'verify' and from 'proof_seal'. It is clear what the tool operates on, though the 'PazAIr' domain is opaque without outside knowledge.

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 'Free, no key' fragment implies the tool can be called without credentials or cost, which is a useful calling condition, but there is no explicit statement of when to use this versus the sibling 'verify' or what a caller must have in hand first. Usage is implied rather than guided.

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