send_message

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

With no annotations, the description bears the full burden of behavioral disclosure. It fails to mention important aspects such as whether the email is sent immediately, whether inbox verification is required, what happens on failure, or any rate limits. The single sentence adds no transparency beyond the obvious act of sending.

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, front-loaded sentence with no unnecessary words. It communicates the core purpose at a glance, which is ideal for conciseness. No structural issues.

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 8 parameters, no annotations, and no output schema, the description is too sparse. It does not explain what the function returns, whether recipients are validated, or how sending behaves in different scenarios. This incompleteness could lead to incorrect usage by an 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 description adds no parameter-level information. Schema coverage is 63%, leaving some parameters (cc, bcc, subject) without descriptions. While these are self-explanatory, the tool description does not clarify relationships between text and html, or whether attachments can be combined with body types, failing to compensate for the coverage gap.

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 'Send a new email from one of your inboxes' clearly states the verb (send), resource (email), and scope (from an inbox). It distinguishes from siblings like reply_to_message and forward_message by specifying 'new email', and from create_draft/send_draft by implying an immediate send action.

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?

No usage guidance is provided. The description does not mention when to use this tool versus alternatives like reply_to_message, forward_message, or create_draft/send_draft. It only states what it does, not when to choose it.

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