cancel_build

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

The annotations already declare destructiveHint=true, idempotentHint=true and openWorldHint=true, so the risk profile is largely covered by structured data. The description adds real value by disclosing the permission prerequisite and the human-confirmation requirement, but says nothing about what happens to build artifacts, logs, or in-flight jobs once cancelled.

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 sentence with the action front-loaded and two parenthetical constraints carrying the safety-critical information. Nothing is padded and nothing needs to move earlier.

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 two-parameter destructive tool this covers purpose, permission requirement, confirmation workflow, and the output schema handles the return value. The only material omission is the post-cancel effect on the build itself, which is left to the annotations to imply.

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 is 50%: 'instance' is documented in the schema as falling back to the configured default, while 'build_id' has no description but is self-evident from the tool name and the integer/minimum constraint. The description itself adds no parameter meaning, which is acceptable here only because the remaining gap is small.

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 names a specific verb (cancel) applied to a specific resource (build) and narrows the scope to 'queued or running' builds. That verb is cleanly distinguishable from sibling mutations like restart_build and bump_build, so an agent can select it without opening 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?

It supplies two concrete operating conditions that govern invocation: the caller needs cancel rights, and the agent should confirm with the user before acting. It does not explicitly say when to cancel versus restart a build, so no exclusions or named alternatives are given.

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