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

No annotations are provided, so the description carries the full burden. It discloses synchronous behavior and scope requirement, but lacks details on rate limits, error responses, idempotency, or what happens on failure. The scope requirement adds value but is insufficient for full transparency.

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 three sentences long, front-loaded with the core action, and every sentence adds value. There is no redundant repetition of schema fields, and the information is well-organized.

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?

With 6 parameters, no output schema, and siblings that overlap in functionality, the description should explain what the tool returns (e.g., success indicator) and prerequisites (e.g., must specify template_id or html_body). The current description omits these details, leaving the agent to infer from 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 description coverage is 100%, so the baseline is 3. The description adds no new information beyond 'using a plantilla and variables', which is already covered by schema. It does not clarify the trade-off between template_id and html_body or the exact format of variables.

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 sends a 1-to-1 transactional email, provides concrete examples (quote, receipt, welcome, reminder), and specifies it uses a template and variables. This differentiates it from siblings like launch_campaign or list_campaigns, which handle bulk or informational emails.

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 identifies the tool for transactional emails (1-to-1) and mentions it is synchronous and requires scope 'send'. It implicitly distinguishes from bulk campaign tools among siblings, but does not explicitly state when not to use it or provide explicit alternatives.

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