mail_send

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

Annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true, so the safety profile is covered. The description earns credit by adding the approval-workflow requirement and the permission scope ('automation:Mail'), which annotations do not convey.

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?

Three compact clauses, front-loaded with the core action before the approval caveat and metadata. The bracketed version/permission tag is slightly noisy but does not bury the essential information.

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?

An output schema exists, so return values need no explanation, and the schema fully documents parameters. The description supplies the approval precondition and permission scope, leaving little an agent needs missing.

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 every parameter including _approvalId and _idempotencyKey is documented in the schema itself. The description names recipient, subject and body but adds no syntax, format or constraint detail beyond what the schema already provides.

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 opens with a specific verb and resource ('Send exactly this recipient, subject and body using Mail') and the word 'exactly' pins down scope. It implicitly distinguishes itself from the sibling mail_create_draft by noting it never auto-sends a draft.

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?

It states the key precondition ('Requires separate human approval; never auto-sends a mutable draft'), which tells the agent this is only invoked after a human gate. It stops short of naming mail_create_draft as the alternative path for staging a message, so routing is clear but not fully explicit.

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