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

Annotations already mark this readOnly, non-destructive and openWorld, so the safety profile is covered. The description adds genuinely useful behavior beyond that: no key required, the receipt is content-hashed and reproducible from the open-source core, and it is Ed25519-signed by a key at a published well-known URL. Missing only error/absence behavior for an unknown id.

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 tightly packed sentences, front-loaded with the core action and immediately followed by the sibling disambiguation and trust model. No filler sentences.

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?

An output schema exists, so return values need not be explained, and annotations carry the safety profile. For a single-param read tool, the description supplies the routing, auth, and verification-model context an agent needs to invoke 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?

Schema description coverage is 100% and the single 'id' param is fully documented in the schema (pattern plus provenance note). The description adds only the phrase 'by receipt id', so it neither compensates nor detracts; baseline 3 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?

States a specific verb (Fetch) and resource (a stored verdict by receipt id) plus the intent (to re-read it), and explicitly differentiates itself from the sibling verify_receipt. An agent can distinguish it from the validate_* and verify_* tools without opening a schema.

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 routes the agent: use this to re-read a stored receipt, use verify_receipt to check genuineness. It also states 'No key', clarifying the auth posture for invocation. It stops short of enumerating when-not-to-use (e.g., what to do if the id is unknown or the receipt is missing).

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