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

Annotations already declare destructiveHint=true, idempotentHint=true, and readOnlyHint=false, so the safety profile is covered without the description. The description adds nothing beyond that – it does not say what cancellation destroys (pending steps, outputs), whether it is reversible, or how in-flight work is handled.

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 single sentence is front-loaded and wastes no words, but its brevity reflects under-specification rather than disciplined concision. Nothing is said that the tool name and title do not already say.

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?

An output schema exists, so return values need not be explained. However, for a destructive mutation in a family of workflow-run tools, the description omits all operational context an agent would need to call it 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?

There is one required parameter, run_id, with 0% schema description coverage, so the description carries the full burden and supplies nothing. Only the schema's uuid format hints at the expected value, which is why this is not a 1.

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 pairs a specific verb ('Cancel') with a specific resource ('workflow run'), so the agent knows exactly what operation it performs. It does not distinguish this tool from the closely-related siblings resume_workflow_run, retry_workflow_run, rewind_workflow_run, or get_workflow_run, which all operate on the same resource.

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?

There is no guidance on when to cancel versus resume, retry, or rewind a run, and no mention of prerequisites such as run state. The agent is left to infer usage entirely from the name.

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