get_verified_user

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

With no annotations present, the description carries the burden of disclosing behavior. It states the authentication requirement, the need to restart the server after setting the API key, and that a previous call may not work until setup is complete. It also clarifies that start_login is not a valid alternative for enabling this tool. It does not describe side effects, but the verb 'get' implies a read-only operation.

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?

The description is compact and front-loaded: the purpose appears in the first sentence, followed by a terse access note. Every sentence conveys necessary information, and there is no redundant phrasing.

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 single-parameter read tool, the description covers the purpose, the identifier key, and the critical setup requirement. It does not explicitly state what the response contains beyond 'their verifications,' nor does it mention error cases. Still, the access quirk is unusual and well documented, making the description largely complete for correct invocation.

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 input schema already describes external_user_id as 'The external user ID' with 100% coverage. The description only repeats the concept 'by external user ID' without adding format, source, or example details. Since the schema fully covers the parameter, a baseline of 3 is appropriate.

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 opens with a specific verb and resource: 'Get a single verified user and their verifications by external user ID.' This clearly distinguishes it from the sibling list_verified_users, which retrieves multiple users, and identifies the exact lookup key.

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 provides explicit access prerequisites: a Proof account, setting PROOF_API_KEY, restarting the server, and calling again. It also directly warns that 'start_login does NOT open this tool,' which is a useful exclusion. However, it does not contrast with related read tools like list_verified_users or get_verification, so the full decision space is not covered.

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