create_api_key

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

Annotations indicate readOnlyHint=false and destructiveHint=false. The description adds critical behavioral info: the full key value is returned only once and must be stored securely. It also explains optional scoping constraints, which go beyond 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?

Two sentences with no wasted words. The first sentence states the purpose, the second adds critical storage warning and optional scoping. Front-loaded and efficient.

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 creation tool without output schema, the description covers the key behavior (one-time return of key) and optional scoping. It could mention that name is required, but the schema covers that. Missing error handling or prerequisites, but still adequate.

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 baseline is 3. The description adds context by explaining that permission can be 'sending_access' and domain_id restricts to a single domain, relating schema fields to usage scenarios. This adds value beyond the schema descriptions.

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 creates a new Resend API key, with specific verb 'Create' and resource 'API key'. It distinguishes from sibling tools like list_api_keys and delete_api_key by focusing on creation and the one-time return of the key.

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 mentions optional scoping to sending-only and single domain, providing context on when to use these features. However, it does not explicitly state when to use this tool versus alternatives like list_api_keys or delete_api_key.

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