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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds value beyond that by disclosing the underlying API route and the exact response envelope, including that each provider embeds its full plans array — important since no output schema exists and the payload is potentially large/nested.

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 compact sentences: purpose first, then endpoint, then return shape. No filler and nothing buried.

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 single-optional-param, read-only list call with no output schema, the description supplies everything needed to call it and interpret the result. Minor omissions: it doesn't say whether the response is paginated or how large the embedded plans list can get.

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 the single optional category_id is already documented in the schema as a provider filter. The description mentions no parameters at all, so it adds nothing beyond the schema; 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?

States a specific verb and resource ("List the addon providers available on Scalingo") and names the endpoint GET /v1/addon_providers, so the agent knows exactly what data comes back. It does not explicitly contrast with the neighboring scalingo_list_addons, which lists an app's provisioned addons rather than the catalog, leaving that distinction to be inferred.

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 parenthetical "databases, monitoring, etc." implies this is a catalog-browsing / pre-provisioning lookup, but there is no explicit statement of when to call this versus scalingo_list_addons or how the optional category filter changes the query. Usage is implied rather than stated.

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