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

Beyond annotations, the description reveals critical behaviors: the api_key is shown exactly once, it must only be stored in MCP client config, invalid/expired/consumed codes return a uniform error, and the operation consumes the code. This exceeds what readOnlyHint/destructiveHint alone convey.

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?

Every sentence earns its place: purpose, constraints, security handling, next steps, and failure behavior. The essential one-time key warning is front-loaded and clearly emphasized.

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?

Given the tool's authentication/consumption complexity, the description covers trigger, constraints, error handling, and post-redeem workflow. The output schema exists, so return-value details are not needed in the description.

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 0%, so the description carries the burden. It fully explains 'email' must correspond to a signup(email) address and 'code' must be the 6-digit code issued within 15 minutes, with attempt limits. Both required parameters are semantically covered.

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: 'Redeem the emailed 6-digit code for a reveal-once workspace API key.' This clearly states what the tool does and differentiates it from signup and get_onboarding_status.

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 explicit usage context: unauthenticated, code must match signup(email), 15-minute validity, 5 attempts max, and instructs to call signup(email) for a fresh code on failure. It also tells the agent exactly what to do after redeem, and names get_onboarding_status as the next step.

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