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

Annotations already declare destructiveHint=true, and the description reinforces the write nature ('MUTATES') while adding value beyond the annotation: the concrete REST endpoint (POST /v1/apps/{app}/deployments), the return shape ({ deployment }), and the absence of a dedicated rollback endpoint. It stops short of disclosing permissions required, whether the call is asynchronous/long-running, or rate limits.

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?

Roughly four short clauses, front-loaded with the mutation warning, then input format, then operational caveat, then endpoint/return. No filler and every element is actionable.

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?

With no output schema, the description usefully states the return payload and the endpoint, and covers the archive-URL requirement plus rollback semantics. What remains missing for a mutating deployment tool is whether the call returns immediately vs. blocks on a build, and any permission prerequisites.

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%, so the baseline is 3, but the description adds real meaning: source_url must be a tar.gz reachable by Scalingo, and git_ref is framed as the handle you re-deploy to roll back. That goes beyond the schema's label-only wording.

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 — 'triggers a new deployment from a source archive URL' — and immediately scopes the input (tar.gz reachable by Scalingo). An agent can distinguish it from scalingo_list_deployments, scalingo_get_deployment, and even from mutation siblings like scalingo_restart_app or scalingo_scale_app because the deployment source is named.

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 task context (create a deployment from an archive) and an important alternative path: rollback is achieved by re-deploying a previous git_ref/archive since no rollback endpoint exists. It does not explicitly compare against scalingo_restart_app, which is the nearest mutation sibling an agent might confuse this with.

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