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

Annotations already declare destructiveHint=true and idempotentHint=false, so the safety profile is known. The description adds one genuinely useful fact beyond that — that already-sent messages are unaffected — but says nothing about what happens to queued or in-flight messages, or whether the cancel can be undone.

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 zero waste; the core action is front-loaded and the caveat follows immediately. Nothing is padded or repeated from the name or annotations.

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 destructive annotations and no output schema, the description covers the essential scope caveat but omits the boundary with pause_batch and the fate of unsent queued messages. An agent can call it, but cannot confidently predict the outcome for a partially sent batch.

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 a single parameter whose schema description ('Batch id') is fully covered, so the schema does the work. The description adds no meaning about the id, such as format or where to obtain it; baseline 3 applies for a fully documented single parameter.

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 batch'), which is unambiguous on its own. It does not differentiate from close siblings like pause_batch or retry_batch, whose semantics differ in ways an agent must infer.

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 statement of when to cancel versus pause or resume a batch, and no prerequisites or exclusions. The second sentence describes a consequence, not a usage condition, so the agent gets no routing guidance.

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