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

Annotations are empty, so the description must disclose behavioral traits. It does reveal prerequisites (token and wallet_fk from /access/login) and encoding requirements (message base64, subject url encoded). However, it does not mention side effects (e.g., email is sent externally), idempotency, rate limits, or error behavior. The fact that it sends an email is implied but not explicitly framed as an action with external consequences.

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 moderately concise but suffers from repetition: 'Sends email to the wallet owner' appears twice verbatim. The rest is a structured parameter list that adds value, but the duplication makes it less polished. A single clear opening plus the parameter breakdown would be more efficient.

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 covers all five required parameters with format and provenance, states the purpose, and notes the return type ('a json object'). For a straightforward email-sending tool, this is nearly complete. It lacks error handling details and doesn't mention the output schema specifically, but the provided information is sufficient for basic invocation.

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?

The schema only lists parameter names and types with zero description coverage. The description adds crucial meaning: api_key is allotted to the application, token and wallet_fk come from /access/login, message must be HTML encoded in base64, and subject must be plain text URL-encoded. This fully compensates for the bare 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?

The description clearly states the tool's function: "Sends email to the wallet owner." This is a specific verb (sends) and resource (email to the wallet owner), which distinguishes it from sibling tools like account_send_sms (SMS) and push_message_send (push notifications).

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 no guidance on when to use this tool versus alternatives. It does not mention that it should be used for emailing the wallet owner specifically, nor does it contrast with sending SMS or push messages. The duplicate phrase 'Sends email to the wallet owner' adds no usage context.

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