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

Annotations already declare readOnlyHint and openWorldHint=false, so safety is covered; the description adds genuinely non-obvious caveats. It discloses that only self-published receipts exist in the log (coverage/recall limitation) and that a seller key is not a verified identity, which materially affects how an agent should interpret results.

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 short sentences: what it does, what a seller query returns, then the caveats. Front-loaded with the primary behavior and no repetition of schema detail.

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?

With no output schema and zero required parameters, the description covers the key interpretation risks (partial log, unverified identity) well. It could mention what happens when no lookup key is supplied (does it list everything?), which is the one gap for an all-optional-parameter 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?

Schema coverage is 100% with descriptive patterns and formats, so the schema already carries the parameter burden. The description clarifies only that 'deliverable hash' equals file SHA-256 and that the seller key is a DID-style identifier, adding modest value beyond the schema.

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 ('Finds countersigned receipts in the public log') and names the three lookup keys, which makes it clearly a read side of the log. It does not explicitly contrast itself with verify_delivery_receipt or publish_delivery_receipt, leaving the boundary to the reader.

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?

Usage is only implied by 'public log' and 'published' – the agent can infer this is a discovery lookup, not verification. There is no explicit when-to-use guidance telling the agent to call this first and then verify_delivery_receipt, which is the most likely routing decision.

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