send-email

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

With no annotations, the description fully discloses that the tool 'SENDS real email immediately and it cannot be unsent', requiring explicit user confirmation. It also mentions the default transport selection logic, which is critical operational 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 structured into clear sections (Use when, Returns, Do not use when, Safety) and every sentence provides value—alternatives, safety, and return information. It is detailed yet economical, with no filler.

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 tool with 8 parameters and significant side effects, the description covers all essential context: when to use, alternatives, safety, and return info. It is complete for an agent to make correct invocation decisions, especially given the presence of an output schema.

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 63%, and the description adds little beyond the schema—it reiterates that recipients are arrays and mentions attachments, but these are already in the schema. The transport default is also already described in the schema, so the description does not significantly enhance parameter understanding.

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 the specific action: 'send a single email now to the given recipients' with optional attachments and transport. It clearly distinguishes from siblings like create-draft, reply-to-message, and send-serial-email by explicitly naming them as alternatives.

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 'Use when' and 'Do not use when' conditions, including specific alternatives for review (create-draft), replying (reply-to-message), and personalized copies (send-serial-email). This leaves no ambiguity about when to invoke the tool.

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