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

Annotations only indicate readOnlyHint and openWorldHint, but the description adds substantial behavioral detail: it returns the complete signed receipt envelope or a structured not-found/unavailable reason, never guesses, and deliberately makes private and unknown IDs indistinguishable. This significantly exceeds what annotations provide.

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 with every sentence earning its place: the action and resource come first, followed by pricing, return behavior, and privacy semantics. No redundant or vague phrasing.

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 simple one-parameter lookup tool with no output schema, the description fully covers input requirements, output behavior, and the sensitive privacy distinction. Nothing material is missing.

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 the parameter is already described, but the description adds the exact format 'OCD-RCP-XXXX-XXXX-XXXX-XXXX', the requirement for an exact ID, and the public-only scope. This goes beyond the schema's own example.

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 description states a specific verb ('Look up') and resource ('public OCD receipt') with an exact ID, and clearly distinguishes public from private receipts. It does not explicitly differentiate from sibling tools like verify_receipt, so it misses full sibling differentiation.

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?

It implies when to use this tool: when you have an exact receipt_id and need a public receipt. It provides useful context ('Free, no payment', 'never a guess'), but it does not explicitly state when not to use it or name any alternative sibling tool.

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