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

The description adds key behavioral details beyond the annotations: the batch size limit (500), the required Postmark server token, and the response format (per-message MessageID, recipient, error code). This meaningfully informs the agent about side effects and partial failures, without contradicting the annotations.

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?

Three sentences pack the action, target API, payload structure, response details, and use-case guidance with no redundancy. Every sentence adds value and the key action is front-loaded.

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?

The description is very complete for a single-parameter tool: it covers purpose, payload format, response semantics, and use cases, and an output schema exists. The only minor gap is the token mention not reflected in the schema, which could cause slight confusion, but overall it is thorough.

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 only defines 'emails' as an array with no item structure. The description compensates by enumerating the Postmark message fields (From, To, Subject, etc.) and the token requirement. However, the token is not in the schema, so the agent may be unsure how to supply it.

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 batch of up to 500 transactional emails in one call to the Postmark delivery API, with a specific endpoint and message field structure. This distinguishes it from the sibling 'send' tool for single 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 explicitly recommends using this tool for bulk receipts, digests, or notification sends, giving clear context. However, it does not explicitly mention when not to use it or name the alternative 'send' tool for single emails.

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