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

Annotations already declare read-only, idempotent, non-destructive behavior, so the bar is lower. The description adds meaningful non-annotation context: the receipt is Ed25519-signed and retrieval is free and does not consume a check. It also lists stored fields, though some of that may overlap with the existing 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?

The description is two tight sentences with zero waste. It front-loads the core operation and appends the cost/quota distinction, making it easy to scan.

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 read operation with rich annotations and an output schema, the description is complete enough. It explains the retrieval, signature, cost behavior, and stored contents without unnecessary detail.

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 description coverage is 100% for the single required parameter, so the schema already explains that receipt_id is a 'rcpt_... from verify_business.' The description adds no format or origin detail beyond naming the parameter, making the baseline 3 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 states a specific verb and resource: 'Returns a stored, Ed25519-signed verification receipt by receipt_id.' It lists the exact contents (inputs, decision, reasons, fact ids, value hashes, rules version, time), and 'Free; does not count as a check' implicitly separates it from check-performing siblings like verify_business.

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 implied rather than stated: the tool retrieves an existing receipt, and 'Free; does not count as a check' hints at when to prefer it over running a new verification. However, there is no explicit when/when-not guidance or named alternative in the description itself; the sibling link only appears in the schema's receipt_id description.

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