Send Email Batch

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

The description adds behavioral context beyond annotations: it specifies a safety requirement (user confirmation) and attachment best practices. It does not contradict any annotations (readOnlyHint=false aligns with sending). While it doesn't mention idempotency or side effects, the annotations already indicate the tool is non-idempotent and non-read-only, so the description provides reasonable added value.

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 highly concise at three sentences, front-loads the core purpose, and every sentence provides actionable guidance. No filler or redundancy.

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's complexity (batch send with two parameters, including a nested messages array), the description covers the essential use case, safety condition, and attachment strategy. An output schema exists (per context), so return-value details are not necessary. It could explicitly mention the batch/single distinction, but the name and title already convey this.

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 coverage is 100%, so the description doesn't need to explain each parameter. It adds a note about preferring attachment IDs, but the schema already states 'Use attachment_id refs for uploaded files.' The description does not significantly enhance parameter understanding beyond what the schema provides, so baseline 3 is appropriate.

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 tool's function with a specific verb and resource: 'send multiple outbound emails in one request.' This distinguishes it from the sibling tool sending_send_email, which handles single emails, by explicitly mentioning the batch capability.

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 provides a clear usage condition ('Use it only when the user confirms every recipient and message') and practical attachment guidance (prefer uploaded attachment_id refs). However, it does not explicitly contrast this with the single-send sibling tool, though the name and context imply the distinction.

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