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

Beyond the annotations (readOnlyHint=false, destructiveHint=false, idempotentHint=true), the description discloses ownership enforcement, row deactivation rather than deletion, and preservation of historical events via recent_alerts. These are meaningful behavioral traits that assist an agent in predicting side effects.

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, and every sentence adds value: the first states the operation, the second covers ownership, soft-delete, and downstream impact. There is no fluff or redundancy.

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 mutation tool with no output schema, the description explains what happens (cancellation), constraints (ownership), side effects (deactivation not deletion), and related context (recent_alerts). Combined with the annotations, it gives an agent enough to invoke correctly and set expectations.

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 for the single 'id' parameter is 100%, and the schema already describes it as a UUID returned by subscribe. The description adds minimal parameter-specific meaning beyond restating 'by id,' so it does not exceed the baseline expected when the schema is complete.

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 uses a specific verb ('Cancel') and resource ('subscription by id'), clearly distinguishing it from sibling tools like 'subscribe' and 'list_subscriptions.' It also states the intended effect (deactivation) and how it differs from deletion, making the purpose unmistakable.

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 provides clear context: use this tool when you need to cancel a subscription by id. It notes ownership enforcement and the soft-delete behavior, which implies usage constraints, but it does not explicitly contrast with alternatives or state when not to use it. The context is clear enough without exclusions.

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