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

With no annotations, the description carries full responsibility. It discloses two behavioral traits: a maximum of 10 emails and a cost of 5 credits. However, it does not mention failure handling, atomicity, or response behavior, which are relevant for an email-sending tool.

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 short sentences, each carrying distinct information: the action/limit and the cost. No filler or 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?

Despite the nested SMTP object, no output schema, and no annotations, the description provides only a bare action, limit, and cost. It omits important context like error handling, partial-send behavior, and response format, making it incomplete for a moderately complex bulk-send operation.

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 50%: only the 'emails' parameter has a description, and the main description merely repeats that max limit. The 'smtp' object lacks any explanation in the schema or description, so the description fails to compensate for the low schema coverage.

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 action ('Envía hasta 10 emails'), the resource ('emails'), and the scope ('en una sola llamada'), distinguishing it from likely single-send siblings. The cost mention adds specificity.

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 implies a batching use case ('hasta 10 emails en una sola llamada') but does not explicitly state when to use this tool versus send_email or send_template, nor any exclusions or alternatives.

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