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

Beyond the annotations (all false), the description adds critical behavioral details: rate limit (3 keys per IP per 24 hours), the need to pass the key as X-Api-Key header, and a warning that the key is shown only once. This fully informs the agent.

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 three sentences, each adding essential information: purpose, usage/limits, rate limit. No wordiness. Front-loaded with key action.

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 simple nature of the tool (1 parameter, has output schema), the description covers generation, limits, key usage, and rate limiting. It is complete for the agent to select and invoke correctly.

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 single parameter 'email' is described in the schema. The description adds that the email is 'used for delivery and repeat-signup lookup,' which provides context beyond the schema's basic description. Coverage is 100%, so baseline is 3; the added context justifies a 4.

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 'Generate a DataNexus API key for the given email address,' which specifies the verb, resource, and context. This distinguishes it from sibling tools like revoke and rotate.

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 context on usage limits (10 free lookups/week for anonymous, 100/week for registered) and important storage instructions. However, it does not explicitly state when not to use the tool or mention alternatives.

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