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

Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false. The description adds a valuable, non-obvious behavioral caveat: 'Best-effort: a run already finishing may still complete.' This goes beyond what the annotations convey and does not contradict them.

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 with no filler. The action and scope are front-loaded, and the best-effort caveat is a compact second sentence. Every word contributes to the agent's understanding.

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 focused cancellation action, the description, full parameter documentation, and annotations together cover cancellation semantics, applicable run states, and best-effort behavior. It does not discuss delete_workflow_run as an alternative, but the output schema and annotations make the definition sufficient 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?

Schema coverage is 100%, with runId, environment, and workspaceId each already documented, including enum values and references to get_me and run_workflow. The tool description itself adds no parameter-specific meaning, but the schema carries the full burden, so 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 queued or in-flight workflow run.' The parenthetical '(workflows group)' helps distinguish this from sibling cancel_classify_run, cancel_extract_run, and cancel_split_run, so the agent can select the right tool without inspecting other schemas.

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 indicates when to use the tool: for queued or in-flight workflow runs. It does not explicitly name alternatives like delete_workflow_run or the other cancel_* tools, so exclusions are implied rather than spelled out, but the state-based context is clear.

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