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

No annotations are provided, so the description carries the burden. It does disclose that a Proof account is required and that client authentication must happen before the tool will work. It does not mention error behavior, whether verifications are embedded in the response, or any other runtime characteristics.

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 purpose is front-loaded in one crisp sentence, and the access note is written in three short, direct sentences. It is compact and contains no filler, though the auth instruction is somewhat tool-specific to Claude Code.

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 simple one-parameter read tool, the description plus schema covers what the tool does, how to authorize it, and the key input. Since no output schema exists, the first sentence's promise of returning the user and their verifications is adequate; a minor gap is that unknown-ID behavior is not described.

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%, so the schema already documents the only parameter. The description simply restates 'by external user ID' without adding format, provenance, or validation details beyond the schema, matching the baseline.

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 clearly states a specific action and resource: 'Get a single verified user and their verifications by external user ID.' The word 'single' helps separate it from list_verified_users, but it never explicitly names or contrasts a sibling tool, so it falls short of a 5.

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 gives a clear auth precondition and explicitly says that start_login does not open this tool, which is useful context. However, it does not tell the agent when to choose this tool over alternatives such as list_verified_users or get_current_user.

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