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

Annotations already provide destructiveHint and idempotentHint, but the description goes further by spelling out what idempotency means in practice: already-finished or already-canceled runs are left unchanged. It also discloses that cancelation_token affects every run associated with the token, which is key behavioral context beyond the annotation flags.

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?

Two short sentences deliver the essential information in order: what the tool does, the parameter selection rule, and idempotency behavior. There is no filler, repetition, or unnecessary elaboration.

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 two-parameter cancellation tool with strong annotations and full schema coverage, the description is sufficient. It covers the action, the parameter constraint, and the idempotency behavior. No output schema exists, but none is needed for an agent to invoke this tool correctly.

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 input schema already documents both parameters and their mutual exclusivity with 100% coverage. The description adds value by emphasizing 'EXACTLY ONE' as a hard invocation rule and summarizing the semantic difference between canceling a single run and canceling every run tied to a token, which helps an agent select the right parameter without opening the schema 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 names a specific verb and resource: 'Cancel journey runs,' which distinguishes this tool from siblings like cancel_automation, cancel_message, and cancel_notification_submission. It also clarifies the two scopes of cancellation (token-wide vs single run), making the tool's 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 gives explicit invocation guidance: supply EXACTLY ONE of cancelation_token or run_id. It also explains the consequence of each choice. It does not explicitly state when to prefer this tool over sibling cancel tools, but the resource-focused name and 'journey runs' phrasing make 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.