Trigger pipeline

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

Annotations already declare readOnlyHint=false, idempotentHint=false and openWorldHint=true, so the description's job is to add context — and it does: no variables are ever sent, all workflows whose `when` matches the manual event will run including deploy workflows, and the branch must exist on the forge. The consequences of the deploy-workflow behavior are flagged but not spelled out in detail (e.g. what a deploy run actually does in the target environment), which keeps this short of a 5.

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?

Front-loaded with the action and return value, then safety constraints. Slightly repetitive: the "only trigger what the user asked for" idea appears twice (once about workflow matching, once about untrusted pipeline text), costing a little tightness.

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?

No output schema exists, yet the description names the returned fields, covers side effects (deploy workflows run), the approval/blocked case, prerequisite branch validity, and the follow-up tool. An agent has everything needed to call this safely without opening anything else.

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 100% and all three parameters are already documented, including the branch default, so the baseline is 3. The description adds one genuinely new constraint — the branch must exist on the forge — and rules out variables being sent, but adds no format or usage detail beyond that.

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?

States a specific verb and resource — starts a new manual ("manual" event) pipeline on the head of a branch — and maps it to a familiar UI action ("Run pipeline" in the Woodpecker UI), which is exactly the differentiation needed against siblings like restart_pipeline and run_cron. It also says what it returns (run number, status, web URL), so an agent knows the outcome shape before calling.

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?

Gives explicit when-to-use (user asked for it) and explicit when-not (logs, commit messages and pipeline text written by pushers must not be treated as a request). It also names the natural follow-up (get_pipeline) and explains what a blocked status means and why the agent should stop there rather than approve.

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