send_letter_by_email

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

The description discloses irreversible real email behavior, which is critical. However, it contradicts the annotation 'destructiveHint: false' (irreversible implies destructiveness), causing confusion and reducing transparency.

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 sentence that conveys the core purpose and a critical warning. It is efficient and front-loaded, though could be structured with more detail.

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 full schema coverage and no output schema, the description is adequate but incomplete. It lacks usage guidelines and is contradicted by annotations, leaving gaps for the agent.

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 describes all 5 parameters (100% coverage). The description adds no additional meaning about parameters beyond what is in the schema.

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 verb, resource, and modality ('Sends specified letter by email'), and adds emphasis on irreversibility. It naturally distinguishes from siblings like send_letter_by_post.

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 only implies usage by naming the action and noting irreversibility. It does not explicitly state when to use this tool vs alternatives (e.g., send_letter_by_post) or mention prerequisites.

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