Check fmsg delivery

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

The description adds valuable behavior beyond the annotations: delivery is asynchronous, pending recipients may still be delivered, non-zero response codes are the remote host's rejection reported verbatim, and recipients added later are included. This gives the agent accurate expectations about dynamic delivery state.

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 two sentences, front-loaded with the core purpose, and every clause adds meaning. There is no repetition of schema or annotation information, and no filler.

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?

For a one-parameter read-only tool with an output schema and strong annotations, the description is complete. It explains the async behavior and response-code semantics, which are the only non-obvious interpretative aspects an agent needs.

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 already documents id as the fmsg message id with 100% coverage. The description adds the semantic constraint that the message must have been sent by this address, which clarifies which ids are valid for this tool.

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 states the exact resource: per-recipient delivery state for a message sent from this address, and specifies the delivered time and response code. This clearly distinguishes it from siblings like get_message or list_sent. The title reinforces the action, making the purpose unambiguous.

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 makes the usage context clear: it applies to messages this address sent and returns per-recipient delivery status. It does not explicitly name alternative tools or state when not to use it, but the context is specific enough for an agent to select it appropriately.

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