cancel_transfer

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

The description discloses the exact failure behavior ('returns error code unsupported (E3)') and the fact that cancellation is not implemented. This goes beyond the annotations, which only say readOnlyHint=false and destructiveHint=false; the description clarifies that the tool is a stub and what an agent should expect.

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?

Two short sentences, with the main action front-loaded and the implementation caveat immediately after. No filler or redundant restatement of the schema.

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 one-parameter stub with an output schema, the description is nearly complete: it states purpose, non-implementation, and exact error code. The only gap is that transfer_id semantics are left to inference, which is minor for such a simple parameter.

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 schema provides only a type and title for transfer_id with 0% description coverage, so the description needed to compensate. It implies that transfer_id identifies the running transfer, but does not explain its format, source, or what makes a transfer 'running'. This is minimal added meaning beyond the schema.

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 the specific verb 'Cancel' with the resource 'a running transfer', clearly identifying the operation. It also explicitly states the tool is not implemented in this build, which is a distinct, unambiguous qualification. The name alone could be ambiguous about whether it lists or cancels transfers, but the description resolves this.

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 clear context: it is meant for canceling a running transfer, and it explicitly states that it is not implemented and will return error 'unsupported' (E3). This effectively tells an agent not to rely on it, although it does not name a sibling alternative.

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