verify_credentials

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

With no annotations, the description carries full burden, and it does disclose the read-only, no-side-effect nature plus what is returned. However it omits auth-failure behavior (e.g. what happens with an invalid token) and any note that this doubles as a credential check, which is the key trait of a verify endpoint.

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 short sentence, front-loaded with the return value and its scope qualifier. No filler, nothing repeated from structured fields.

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 zero-parameter read-only call with no output schema, the description gives what an agent needs: the returned entity and its authenticated scope. It is slightly thin on return shape and error behavior, but those are minor for a tool this simple.

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 baseline of 4 applies; there is nothing for the description to disambiguate beyond what the empty schema already conveys.

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 ('Return the authenticated Fanfou account') with the scope qualifier 'authenticated', which distinguishes it from sibling get_user. It doesn't explicitly name that sibling, so it falls short of the top mark.

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?

Usage is only implied: the word 'authenticated' hints this is the identity/auth-check call rather than an arbitrary profile lookup. There is no explicit when-to-use or when-not-to-use statement and no reference to get_user as the alternative.

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