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

Annotations already declare destructiveHint=true, but the description adds the behavior that actually matters: it stops at the next safe point rather than abruptly, and preserves whatever was already graded. That nuance is unavailable from any structured field and directly informs the agent's decision to call it.

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 tight sentences with the core action front-loaded and the behavioral caveat immediately after. The trailing "Answers: how do I stop..." is largely redundant with the opening sentence, though it aids intent matching.

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 destructive tool with annotations covering the safety profile and no output schema, the description covers action, precondition, and post-call state well. It stops short of saying whether the cancelled journey can be resumed or what the response contains.

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?

Only one parameter (reportId) with 100% schema description coverage, so the schema fully documents it. The description adds no format, source, or lookup guidance for obtaining the report id, which is the baseline-3 outcome when the schema does the work.

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?

States a specific verb+resource ("Stop a charging journey") plus a scope qualifier ("still running on this account"), which separates it from run_journey and list_runs without naming siblings explicitly. An agent can identify the operation, though no sibling is called out by name.

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 precondition "still running" tells the agent when this applies and implicitly excludes completed/failed journeys. No explicit alternative is named for the non-running case (e.g., where to look up a finished run), which keeps it short of a 5.

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