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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds that the hash computation is deterministic, but it does not disclose what happens for malformed receipts, whether it returns a match result, or how errors are surfaced. It does not contradict the annotations.

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 one short sentence and the core operation is front-loaded. The 'FREE' prefix is extraneous but does not create meaningful bloat. Overall it is efficient and easy to parse.

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?

With no output schema, the description should clarify what the tool returns (e.g., a boolean match, a recomputed hash, or an error), but it does not. The receipt parameter's internal structure is also unaddressed, leaving the agent without enough context to confidently call the tool on potentially malformed input.

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 input schema has one required 'receipt' object with 0% schema description coverage, and the description only calls it a 'CrossingKey receipt' without explaining required fields or structure. The agent is left to infer what the receipt object must contain for the hash recomputation to work.

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 names a specific operation ('recomputes') and a specific resource ('deterministic result hash embedded in a CrossingKey receipt'), which clearly differentiates it from sibling list/get/describe tools. It tells an agent exactly what action this tool performs.

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 gives no guidance about when to use this tool versus alternatives like xkey_validate_intake or fulfillment.get. The 'FREE' prefix is not usage guidance. It neither specifies conditions that select this tool nor rules out other tools.

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