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

Annotations already indicate destructiveHint=true and readOnlyHint=false, so the bar is lower. The description adds important context: it only applies to requests the caller sent, implying the request must still be pending. This goes beyond what annotations convey without contradicting them.

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 that conveys the action, resource, and scope. No redundant words or repetition of the title or 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?

This is a simple, single-parameter tool with an output schema and adequate annotations. The description, together with the schema and annotations, fully covers what the tool does and its precondition (previously sent request). No significant information gaps remain.

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 already provides 100% coverage with a clear description for userId ('Argo user ID of the counterparty'). The tool description does not add parameter-specific syntax or constraints beyond implying the request must exist, which is contextual rather than a semantic enrichment of the parameter itself.

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 'cancel' with the resource 'friend request' and adds the critical qualifier 'you previously sent,' which clearly distinguishes this from accept_friend_request and reject_friend_request for incoming requests. This leaves no ambiguity about the tool's function.

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 phrase 'you previously sent' provides clear context that this tool is for outgoing requests, implicitly contrasting with accept/reject for incoming ones. However, it does not explicitly name alternatives or state when not to use it, so it stops short of full guidance.

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