send_email

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It only states the action without explaining side effects, permission requirements, rate limits, or what happens on success/failure. As a send operation, it implies mutation, but the description does not clarify whether the email is queued, sent synchronously, or if there are constraints like max recipients. This is a significant gap for a mutating tool.

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 a single concise sentence with no waste. However, it is under-specified rather than efficiently complete. It front-loads the core action but lacks any additional structural elements like examples or caveats. It is not verbose, but the brevity compromises informativeness, so a middle score is appropriate.

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?

This tool has two nested object parameters, no output schema, and no annotations. The description is minimal and does not explain the expected format of the 'from' object, whether 'to' supports multiple recipients, or what the tool returns (e.g., an email ID). Given the complexity of the schema and the absence of annotations, the description should provide more guidance to be considered complete. It leaves too many details to inference.

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 provides 100% coverage for both parameters with descriptions of their structure ('to' as recipients with identity/email, 'content' with subject, html, from). The tool description adds no extra semantic meaning beyond what the schema already specifies, so the baseline of 3 applies. The nested object formats are already explained in the schema, so the description does not need to reiterate them.

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 action (send), the resource (email), and the target (specific users). It distinguishes from sibling messaging tools like send_push, send_sms, and send_whatsapp by naming the medium, though it doesn't explicitly contrast with them. The phrase 'directly to specific users' adds a useful nuance that it is not a bulk campaign, but it could be more specific about scope.

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 no guidance on when to use this tool versus alternatives. There are many sibling tools (send_push, send_sms, send_whatsapp, create_campaign), but the description does not mention any conditions that would select email over others, nor any exclusions such as 'use create_campaign for bulk sends'. The phrase 'directly to specific users' implies a use case, but it stops short of explicit direction.

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