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

Annotations already flag destructiveHint=true, but the description goes well beyond them: it discloses the immediate side effect on the link, the conditional callback firing, and the irreversibility ('never reopens'). For a mutation tool this is exactly the extra context an agent needs before committing.

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 dense sentences, front-loaded with the effect and consequence, then permanence, then precondition and return. No filler and nothing that restates the name.

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 still tells the agent what comes back (the request plus `next`), and it covers side effects, irreversibility, and preconditions. Nothing material for correct invocation is absent.

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 coverage is 100% with only two parameters, both fully documented in the schema, so the description legitimately cedes that ground. It adds only a return-value note ('Returns the request plus `next`') rather than parameter syntax, which matches the baseline 3 when the schema does the heavy lifting.

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 (cancel) and resource (pending request) and immediately specifies the observable consequence: the link stops working and a request.canceled callback fires. This is far more precise than the bare name/title and clearly distinguishes it from request_create/request_remind in the sibling set.

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?

Gives an explicit precondition ('Only pending requests can be canceled') and routes the agent to a follow-up alternative ('ask again with request_create'). What is missing is guidance on the sibling tools for non-pending requests (request_get/request_list) and any note that a reason is optional.

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