send_email

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

With no annotations provided, the description carries the behavioral disclosure burden. It reveals key operational constraints: the from address must be on a verified domain, and an omitted from falls back to the server default sender. These are genuinely useful, non-obvious behaviors beyond the schema, though it does not mention what response is returned or failure consequences.

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?

Two sentences with no fluff. The primary action and endpoint are front-loaded, followed by a compact capability list, and the most important prerequisite (verified domain) is stated clearly. Every sentence earns its place.

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?

For a send action with no output schema, the description covers the core operation, supported content types, key delivery options, and a domain-verification prerequisite. It is slightly thin on post-send behavior or return value, but given the rich schema descriptions and the tool's straightforward purpose, it is largely complete.

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 85%, so the schema already documents most parameters. The description summarizes the feature set (HTML/text, CC/BCC, reply-to, scheduling, attachments, tags, headers) and adds important meaning about the from behavior, but it does not need to restate each parameter. It adds some value without fully compensating for the undocumented portions.

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 states a specific verb and resource — 'Send a single email through SendHustle (POST /emails)' — and explicitly scopes it to a single email, distinguishing it from the sibling send_batch_emails. It also enumerates the supported capabilities, so an agent can clearly understand what the tool does.

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 phrase 'single email' provides clear context for when this tool is appropriate versus batch sending, but it does not explicitly name send_batch_emails or state when not to use it. It gives good usage context without formal exclusion or alternative guidance.

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