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

No annotations are provided, so the description carries the full burden. 'Fetch' implies a read-only operation, but the description does not disclose behavior for missing receipts, error cases, response format, or authentication requirements.

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?

A single, front-loaded sentence with no filler. Every word contributes to stating the operation and its core identifier.

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 id-based fetch with only two parameters, the description is minimally adequate when combined with the schema. However, with no annotations and no output schema, the lack of return/error/authorization context leaves meaningful gaps for an agent deciding whether the call succeeded or how to handle failures.

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 phrase 'by id' reinforces that receiptId is the lookup key, adding a small amount of meaning to that otherwise undocumented parameter. The optional key parameter is already described in the schema, so the description partially compensates for the 50% schema coverage but adds no new detail about formats or constraints.

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 uses a specific verb ('Fetch') and a distinct resource ('receipt') with an id-based lookup, which clearly separates it from broader sibling operations like list_transactions. It does not explicitly name an alternative, so it falls just short of 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?

No guidance is given about when to call this tool versus siblings such as list_transactions or service_quote. There is no mention of prerequisites, such as obtaining a receiptId from a prior transaction.

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