Create API Key

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

With no annotations, the description discloses the critical behavioral trait that the token is only shown once and must be displayed to the user. This is beyond what the input schema conveys and is essential for correct usage. However, it does not disclose other potential behaviors like required permissions or response format.

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 exactly two sentences: the first states the core action, and the second delivers a crucial user-facing warning. No filler or redundant content, making it highly concise and front-loaded.

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 description provides the essential context for a create operation: it identifies the resource, and the one-time token disclosure alerts the agent to a critical user-facing requirement. However, with no output schema, it doesn't explicitly describe the response structure beyond the token, and it omits any prerequisites or error scenarios. For a simple tool, this is largely sufficient but not exhaustive.

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 input schema already provides descriptions for all three parameters with 100% coverage. The description adds no additional parameter-specific semantics, so it does not go beyond the schema. Baseline of 3 applies given high schema coverage.

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 'Create a new API key in Resend,' identifying the specific verb and resource. This distinguishes it from sibling tools like list-api-keys and remove-api-key. The added note about the one-time token further clarifies the tool's purpose.

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?

There is no explicit guidance on when to use this tool versus alternatives, such as mentioning that listing or removing keys are separate operations. The description implies usage ('Create a new API key') but provides no exclusions or comparison to sibling tools.

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