Send Email

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

No annotations are provided, so the description carries the full burden. It discloses the immediate/scheduled sending behavior, return value ('Send confirmation and email ID'), and post-send follow-up (use list-emails or get-email). However, it does not mention edge cases like failures, retries, or rate limits, which could be important for a send operation.

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 well-structured with bold headers and bullet lists, and the purpose is front-loaded. It is longer than strictly necessary ('Key trigger phrases' overlap somewhat with 'When to use'), but every section adds value for a tool with 14 parameters and many sibling alternatives.

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 lack of an output schema and the tool's complexity (14 params, nested objects), the description covers the essential context: return value, workflow after sending, alternatives, trigger phrases, and scheduling. It tells the agent what to do with the result (check status via list-emails/get-email) and when not to use it, providing a complete operational picture.

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 the baseline is 3. The description itself does not elaborate on individual parameters, but the schema provides detailed descriptions for all 14 parameters, including examples and constraints. The description adds no extra parameter-level meaning beyond what the schema already gives.

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 explicitly states 'Send a single transactional email to one or more recipients immediately (or schedule it)' with a specific verb and resource, and distinguishes from siblings by noting 'NOT for: Sending the same email to a whole list/audience (use create-broadcast + send-broadcast).' This makes the tool's scope unmistakable.

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?

Provides explicit when-to-use guidance ('When to use' bullet list) and exclusions ('NOT for' section) naming alternative tools. Also includes workflow and trigger phrases, making it clear when to select this tool over siblings.

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