Trigger a pipeline

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

Annotations already declare destructiveHint=true and idempotentHint=false, but the description adds real context on top: the exact failure mode (bare 400 for nonexistent branch), the concrete retry hazard (a retry starts a second pipeline because Woodpecker has no idempotency key), and the event='manual' semantics. No contradictions with annotations.

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?

Four sentences, each carrying distinct information: core action, failure mode with mitigation, idempotency limitation, and post-call verification. The most decision-relevant fact (what it does and scope) is front-loaded, and there is zero redundancy or filler.

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?

Given that an output schema exists (so return values need no explanation) and annotations cover the safety profile, the description covers everything an agent needs: exact behavior, failure behavior, idempotency consequences, and both pre- and post-call checks referenced to sibling tools. Nothing material is missing for correct 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 all four parameters (branch, message, repo_id, variables) are already fully documented, including the flat string-to-string constraint on variables. The description adds one useful bit of parameter-related context—that an invalid branch yields a bare 400—but otherwise adds no per-parameter meaning beyond the schema. Baseline 3 is appropriate.

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 ('Starts a pipeline manually on a branch') and adds a distinguishing detail: the config runs as it exists in that branch right now with event 'manual'. This clearly separates it from siblings like restart_pipeline (existing pipeline), run_cron (scheduled), and cancel_pipeline (opposite action).

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 gives explicit operational guidance: check list_repository_branches before calling to avoid the bare-400 failure, and read list_pipelines before retrying to avoid duplicate runs. It names concrete sibling tools for pre- and post-call validation. It falls just short of 5 because it never explicitly contrasts with restart_pipeline or run_cron as alternatives for different scenarios, leaving some sibling differentiation to the agent.

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