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

With no annotations, the description carries the full burden, and it does disclose one genuine behavioral trait: the tool is a no-op on terminal builds. It omits other material traits for a mutation — permission/auth requirements, whether cancellation is reversible, whether it is synchronous or streaming, and what happens to partial build artifacts.

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 sentences, zero filler, with the core action front-loaded and the edge-case constraint immediately following. Every clause 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 single-parameter build control tool with no output schema, the description covers the action and the key edge case, which is close to sufficient. It would be complete with a note on return/confirmation behavior and any auth requirement, given there are no annotations to cover those.

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 required parameter with 100% schema description coverage ('ID of the build to cancel'), so the schema already does the work. The description adds no format, source, or lookup guidance for buildId, which is the baseline 3 case.

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 gives a specific verb+resource ('Cancel a running build'), which is unambiguous and clearly distinct from the build/retry/continue siblings by verb. It stops short of naming an alternative like retry_build or continue_build, so an agent must infer sibling routing from the verb alone.

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 an explicit applicability condition ('running build') and an explicit negative case ('no effect on builds that already reached a terminal state'), which tells the agent when the call is a no-op. It does not name alternative tools for the terminal-state case (e.g., retry_build), so routing guidance is incomplete.

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