send_email

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

Annotations already indicate this is a write, non-destructive, non-idempotent operation. The description adds the SMTP protocol detail but does not elaborate on behaviors like error handling, rate limits, or attachment limits. With annotations covering the safety profile, the description adds minimal extra context.

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 extremely concise: two sentences. The first sentence states the primary purpose, and the second provides a key usage guideline. No wasted words.

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 has 10 parameters, all described in the schema, and an output schema exists (not shown but noted), the description is nearly complete. It misses some details like return value or attachment processing, but the core functionality is clear.

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 description coverage is 100%, so all parameters are already documented. The description does not add any additional meaning beyond the schema, hence baseline score of 3.

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 sends an email via PrivateEmail SMTP, specifying the verb 'send' and the resource 'email'. It distinguishes from siblings by explicitly recommending 'reply_email' for threaded replies.

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 explicit guidance: 'Prefer reply_email for threaded replies', indicating when not to use this tool and offering an alternative. This helps the agent choose correctly.

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