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

Annotations already declare destructiveHint=true, and the description reinforces it with 'MUTATING' while adding operational detail: the default build source, optional targets, and the exact POST endpoint. It does not contradict the annotations, and it provides enough side-effect context for an agent to know this is a mutating infra action.

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 compact and front-loaded with the mutating nature and core purpose. The endpoint line is useful but somewhat redundant with the tool name/title, and 'MUTATING' repeats destructiveHint/title, so it is not perfectly waste-free.

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 5-parameter mutation tool with destructiveHint and no output schema, the description covers the essential calling context: target resource type, default behavior, optional targeting, and HTTP verb/path. It does not describe response shape or prerequisites such as repository configuration, but those are adequately implied for this trigger operation.

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 baseline is 3, but the description adds a meaningful synthesis: an empty body means build the latest commit on the linked branch, and only branch, sha, or pullRequestId are used for targeting. This clarifies the relationship and default behavior beyond the individual parameter descriptions.

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?

Description uses a specific verb+resource: 'start a new build for a build/combined service', which makes the operation unambiguous. It is clearly distinct from sibling tools such as list_service_builds, pause_service, restart_service, and scale_service, 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?

The description frames the tool as MUTATING and explains the default call semantics: an empty body builds the latest commit on the linked branch, with optional alternatives for branch, SHA, or pull request. It gives clear context for when to use it, though it does not explicitly name exclusion conditions or alternative tools.

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