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

Annotations already declare the safe read-only profile (readOnlyHint, idempotentHint, destructiveHint=false), so the description earns credit for adding genuine behavior: the incoming/outgoing split and the privacy guarantee that only the counterpart's name is returned, never their email. It omits any note on result size or pagination, keeping it just shy of a 5.

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 sentences, each doing distinct work: what is listed and how it is split, what the return contains, and which siblings consume the request_id. Front-loaded and waste-free.

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 carries the return-shape burden and does so by describing the incoming/outgoing structure and the request_id field. The only gap is absence of pagination or volume guidance for a potentially unbounded list, which is minor.

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 tool takes zero parameters, so the schema has nothing to explain and the baseline is 4. Nothing in the description needs to compensate for missing parameter documentation.

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 and resource ('List the authenticated user's pending friend requests') and immediately adds the meaningful scope distinction of incoming vs outgoing. An agent can distinguish this from friends_list and the accept/decline/resend siblings without opening any schema.

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?

Explicitly routes the agent downstream ('Use the returned request_id with friend_request_accept / friend_request_decline / friend_request_resend'), which is strong when-to-use guidance. It stops short of stating when not to use this tool or contrasting with friends_list, so it is clear context without explicit exclusions.

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