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

Annotations already declare readOnlyHint=true and destructiveHint=false, indicating safe read-only behavior. The description adds value by detailing the content of the explanation (fields, outcomes, verification commands, signature limitations) and the preparatory usage instruction, which goes beyond what annotations convey.

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?

The description is two sentences with no superfluous words. It front-loads the purpose in the first sentence and adds usage guidance in the second. Every part earns its place, achieving maximum conciseness for the information conveyed.

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?

Given the tool's simplicity (no parameters, no output schema, read-only), the description fully covers what an agent needs: the tool's purpose, the specific topics it explains, and a usage hint. No additional details are necessary for correct invocation or understanding.

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 tool has zero parameters, so the schema coverage is trivially 100%. The description does not need to elaborate on parameters. It correctly does not introduce contradictory parameter information and the baseline score of 4 is appropriate.

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 explicitly states it explains the receipt format, listing specific aspects: fields, outcomes, verification commands, and what a signature does not establish. This clearly distinguishes it from sibling tools like decode_receipt and verify_receipt, which perform actions rather than provide explanatory information.

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 description includes the directive 'Use before describing the format,' providing a clear contextual cue for when to invoke this tool. However, it does not explicitly mention when not to use it or name alternative tools for different tasks, though the context is strong enough for an agent to infer.

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