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

Annotations already indicate the operation is not read-only and not destructive; the description adds the important billing context ('billed as a test run'), but it doesn't disclose whether the test run creates state, logs, or has other side effects on the draft agent. This is acceptable but could be richer.

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?

A single, front-loaded sentence that conveys the action, target, outcome, and billing implication with no wasted words.

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 tool is simple, both parameters are fully documented by the schema, annotations cover safety semantics, and the description explains the tool's purpose and billing side effect. Everything an agent needs to call it correctly is present.

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 100%, with both 'message' and 'agent_id' clearly described in the schema. The description's phrasing adds light context ('test message', 'draft') but doesn't meaningfully go beyond the structured parameter definitions.

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 uses a specific verb ('Send a test message') and identifies a precise resource ('a draft'), while clarifying that the tool returns the real runtime reply. It naturally distinguishes itself from siblings like probe_deployment by targeting drafts rather than deployments.

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 clearly conveys when to use the tool: when you need to test a draft agent with a real message and get the runtime's reply. It does not explicitly name alternatives or when-not-to-use conditions, but the draft-vs-deployment framing makes the intended context clear.

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