send_email

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It excellently describes multiple behavioral traits: markdown-to-HTML conversion, error handling for read_only mode (403 with upgrade instructions), and gated oversight behavior (pending_approval status with no-retry policy). This provides comprehensive behavioral context beyond basic functionality.

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 efficiently structured with three sentences, each serving a distinct purpose: core functionality, error handling, and approval workflow. There's zero wasted language, and critical information is front-loaded about the main sending functionality before detailing edge cases.

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 mutation tool with no annotations and no output schema, the description provides exceptional completeness. It covers the core functionality, input format (markdown), error scenarios (403, pending_approval), and behavioral constraints (no retry). This gives the agent sufficient context to use the tool correctly despite the lack of structured metadata.

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 schema description coverage is 100%, so the baseline is 3. The description doesn't add specific parameter semantics beyond what's in the schema, though it does mention markdown format for the body which aligns with the schema's 'markdown' parameter description. No additional parameter context is provided.

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 specific action ('send an email'), identifies the resource ('from your MultiMail address'), and distinguishes it from siblings like 'reply_email' or 'check_inbox' by focusing on sending new emails. It provides additional context about markdown conversion that further clarifies its unique function.

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 description explicitly provides when-to-use guidance by mentioning the 'read_only mode' scenario (returns 403 error) and directing users to 'use request-upgrade' as an alternative. It also explains the 'pending_approval' status for gated oversight mailboxes and explicitly states 'Do not retry or resend' in that case, providing clear usage boundaries.

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