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

The annotations already signal a mutating action (readOnlyHint=false) and non-idempotency (idempotentHint=false), so the description only needs to add context. It usefully discloses the sandbox pause side effect, but it does not explain reversibility or whether the run can later be resumed.

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?

A single crisp sentence with no filler. The core action and the non-obvious sandbox-pause effect are both front-loaded, and every word earns its place.

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 low-complexity two-parameter cancel action, the definition covers the action, the side effect, and the main state constraint. There is no output schema, so return behavior is not described, but annotations cover idempotency/safety signals and the schema covers parameters, leaving no critical gap for 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 description coverage is 100%, so the schema carries the parameter documentation burden. The builder_run_id description is generic, while the status description adds the key constraint ('review-pending changes must be declined instead'); the tool description itself adds no further parameter meaning.

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 specific verbs and resources: 'Cancel a running builder run' plus the explicit side effect 'pause its sandbox'. This clearly differentiates it from siblings like resumeBuilderRun and general stopRun without needing to open the schema.

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 phrase 'running builder run' establishes a clear precondition, and the status parameter description adds an exclusion: review-pending changes must be declined instead. It does not name an alternative tool, but the context is concrete enough to route an agent correctly.

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