send_email

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

With no annotations, the description carries full responsibility for disclosing behavioral traits. It only states the action 'Send an email' and mentions credential sources. It fails to disclose side effects (e.g., sending is destructive), error behavior, rate limits, or whether the operation is idempotent. This is insufficient for an agent to understand runtime implications.

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 very concise at one sentence (16 words) and front-loads the main purpose. It earns its place without unnecessary words. However, it could be slightly expanded to include key behavioral info without harming conciseness, so it is not a perfect 5.

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?

Given the tool complexity (5 parameters, 1 required, no output schema) and no annotations, the description is far from complete. It omits what the tool returns (e.g., success/error response), how to obtain template IDs, whether it works offline, and how it relates to siblings (e.g., using get_email_history to check sent emails). It needs much more context for an agent to use it reliably.

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?

Input schema coverage is 100%, so the baseline is 3. The description adds that credentials can be passed as parameters or from env vars, which is already implied in the schema descriptions (e.g., 'Overrides EMAILJS_SERVICE_ID env var'). No additional meaning is provided; it does not clarify how template_params map to variables or when to use overrides.

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's function: 'Send an email using an EmailJS template.' It uses a specific verb ('Send') and resource ('email using EmailJS template'), which immediately distinguishes it from sibling tools like get_email_history (reading) and validate_config (validating).

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 provides a minor usage hint about credentials (can be from env vars or parameters) but does not explicitly say when to use this tool vs. alternatives. It lacks guidance on prerequisites (e.g., valid template ID) or when not to use it. No comparison to siblings is made.

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