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

With no annotations provided, the description carries the full behavioral burden and does so well. It discloses the refund side effect, the 409 behavior for already-terminal simulations, the fact that closing the session does not stop the run, and the special re-run refund behavior with results_kept: true.

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 definition is front-loaded with the action and refund effect, then uses a short bullet list for usage conditions and a compact paragraph for edge cases. Every sentence adds operational value and there is no wasted prose.

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 single-parameter cancellation tool with no annotations or output schema, the description is complete enough. It covers the action, side effect, session-close misconception, error behavior, and re-run results behavior, leaving no major ambiguity for correct 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 has 100% description coverage and already documents sim_id as the running simulation id. The description reinforces that the target is a running simulation but adds no syntax, format, or validation detail beyond the schema, so the baseline 3 is appropriate.

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 a specific verb and resource: cancel a running simulation and refund the wallet reservation. It also distinguishes this explicit cancellation from merely closing the MCP session, which is a critical scope distinction.

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?

It gives explicit when-to-use scenarios such as user changes their mind, wrong parameters, or a debate going off the rails. It also gives a clear when-not-to-use warning: closing the session does not cancel, and the tool should only be called if the user genuinely wants to stop the run and refund credits.

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