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

Annotations only declare readOnlyHint=true; the description goes further by naming the concrete fields returned (status, git_ref, pusher, image size, timestamps) and the response envelope 'Returns { deployment }', which matters because there is no output schema. It does not cover failure behavior (e.g. not-found for an invalid deployment_id) or pagination, which are minor for a single-resource GET.

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?

Three short, front-loaded sentences with no filler; the field list and return shape are the most useful parts and come first. The raw API path partly duplicates the parameters but is cheap and useful for agents mapping to Scalingo's REST API.

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 simple two-parameter read tool, the definition covers what it returns, which resource it targets, and the underlying endpoint, while annotations carry the safety profile. Only failure modes and any caching/freshness behavior are unstated, which is a small gap given the tool's simplicity.

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%, with both app (name or app-… id) and deployment_id already documented in the schema. The description restates the path template GET /v1/apps/{app}/deployments/{deployment_id} but adds no new semantics such as id format or validity rules, so the baseline 3 applies.

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 opens with a specific verb and resource ('Fetch a single deployment's details') and enumerates the returned fields, so the agent knows exactly what it gets. 'Single' implicitly contrasts with the sibling scalingo_list_deployments, but the sibling is never 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?

Usage is only implied: 'a single deployment' suggests this is the detail lookup versus the list tool, and the required app + deployment_id make the precondition obvious. There is no explicit when-to-use/when-not guidance or named alternative, so the agent must infer the routing from the sibling list.

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