send_email

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

The description discloses plain text only, max lengths (10k body, 200 subject), cost (200 sats), payment method (Bitcoin Lightning), no SMTP/domain needed, and the prerequisite of create_payment. With no annotations, this provides good behavioral context.

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 concise, front-loaded with purpose, then constraints, then payment details. Every sentence adds value without 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?

The description covers prerequisites, constraints, and use cases, but does not mention return values or error handling. No output schema exists, so more context on expected output or errors would improve completeness.

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% with clear descriptions. The description adds context about the payment flow (requires create_payment with toolName='send_email') and reiterates limits, but does not significantly enhance parameter meaning beyond the schema.

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 that the tool sends an email ('Reach anyone with an email address') and specifies its use for formal communication, reports, and contacting people outside chat, distinguishing it from siblings which are mostly multimedia tools.

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 explicitly mentions when to use this tool (formal communication, reports, contacting outside chat) and implies that it's for email, but does not exclude alternatives or explain when not to use it. Given no other email tool exists, this is adequate.

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