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

Annotations only mark readOnlyHint=false and destructiveHint=false, but the description adds crucial behavioral details: idempotency ('returns the same result'), irreversibility ('cannot be resumed'), and persistence ('record stays visible in list_workflows'). It also explains the impact on resume_workflow's active listing, which annotations cannot convey.

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 description is two sentences, front-loaded with the core action, then condenses essential caveats (idempotency, resume exclusion, listing visibility) into a compact, well-structured format. Every sentence adds value.

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 simple single-parameter cancellation tool with an output schema, the description covers the core operation, irreversible side effects, idempotency, and the relationship to sibling tools (resume_workflow, list_workflows). It is complete enough for an agent to invoke safely and 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 has 100% parameter description coverage, including how to obtain workflow_id and how to recover a lost id. The description adds no additional parameter semantics beyond what the schema already provides, so the baseline score of 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 opens with 'Cancel an active workflow by id', a specific verb+resource combination. It distinguishes itself from resume_workflow by noting cancelled workflows cannot be resumed and are excluded from its active listing.

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 clearly states when to use the tool (to stop an active workflow) and implicitly warns against use if resumption may be needed ('cannot be resumed'). However, it does not explicitly name alternative tools or provide a when-not-to-use list beyond the resumption caveat.

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