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

The description discloses key behavioral traits beyond the annotations: the server does not adopt the new pair as the session credential, reuse revokes the family, and 409 is benign. This adds significant context about side effects and retry semantics that annotations alone do not convey. No contradiction with annotations.

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: it states the core action first, then error semantics, then a security warning. Every sentence earns its place, and there is no redundant repetition of schema or annotation information.

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 tool with no output schema, the description covers the essential context: what the tool does, how to handle errors, side effects, and security precautions. An agent has enough information to invoke it correctly and interpret failures.

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% and the only parameter (refresh_token) is self-explanatory. The description adds context about the token's role and error behavior, but the parameter itself is already clear from the schema. Baseline 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 states a specific verb ('Exchange') and resource ('a refresh_token for a new access/refresh pair'), clearly distinguishing it from sibling auth tools like login or getSiweNonce. It also names the exact error conditions, making the tool's purpose unambiguous.

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 explicitly explains when to use the tool (to exchange a refresh token) and provides critical guidance on handling errors: 401 means the token was reused and the family is revoked, while 409 refresh_raced is benign and should be retried with the latest stored token. It also warns against logging tokens, which is a clear operational guideline.

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