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

With no annotations, the description carries the full burden. It discloses key behaviors: the contribution is marked 'colony_username_verified' on a match, the raw API credential is never sent, and the token exchange endpoint is specified. It does not describe failure modes or reversibility, but the disclosed details exceed typical tool descriptions.

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 moderately long but every sentence adds value. It front-loads the purpose, then gives the token-exchange instructions and requirements. It could be tightened, but it is not wordy or redundant.

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?

The tool involves a complex OAuth token exchange and multiple required parameters. The description explains the auth flow well but leaves merge_id and parent_id undefined, which is a significant gap for a tool with no output schema and no annotations. It is not fully complete.

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 description coverage is only 25% (only id_token has a description). The description clarifies id_token ('the audience-scoped id_token') and token ('your participant_token or owner_token'), but merge_id and parent_id are left unexplained. Since the schema is sparse and the description doesn't fully compensate, a 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 clearly states the tool's purpose: 'Prove this contribution controls the Colony username it claims.' This is a specific verb+resource combination that distinguishes it from siblings like verify_certificate, which targets a different verification type.

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 preconditions and a step-by-step flow: 'FIRST exchange your Colony API JWT for an id_token via RFC 8693 token exchange... then pass ONLY that id_token here.' It also notes the required participant_token/owner_token. However, it does not explicitly name alternatives or when-not-to-use this tool, so it falls short of a 5.

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