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

Explicitly explains the critical test_mode behavior (default true means no real emails; false sends legally-binding requests). Annotations only provide destructiveHint=true, so the description adds essential context about real-world impact and testing.

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?

Two sentences with no extraneous information. The main action is front-loaded, and the critical caveat about test_mode immediately follows.

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?

Explains purpose and test_mode, but does not describe the return value or success/failure indicators. Given no output schema, the agent lacks information about what the tool returns after sending.

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 schema already documents all parameters. The description reiterates test_mode behavior but adds no new 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?

Clearly states it sends a signature request built from templates, with a specific verb and resource. Distinguishes from all sibling tools (list, get, cancel, remind) by unique action and mentions the API endpoint.

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?

Identifies this as the tool for sending from templates, which is distinct from siblings. No explicit when-to-use or alternatives, but the context (only send tool) makes it clear. Could mention prerequisites like needing a template ID from list_templates.

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