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

Annotations already declare readOnlyHint=true, so the safety profile is covered and the description's addition of the raw endpoint is minor context. It does not disclose what happens when the code does not exist or what shape the response takes, which is the remaining behavioral gap.

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?

Two terse sentences with the core action front-loaded and the endpoint reference appended; nothing is wasted and the key constraint comes first.

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-parameter read tool with annotations carrying the safety profile and no output schema, this is essentially sufficient. Slightly more could be said about the not-found case, but nothing essential for calling it correctly is missing.

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% and the sole 'code' parameter is documented as 'The plan's unique code.' The description's 'by code' only restates that, adding no format, casing, or lookup semantics beyond the schema.

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 (Retrieve) and resource (a single plan) scoped by code, and adds the concrete API mapping GET /plans/{code}. It implicitly contrasts with lago_list_plans via 'a single plan', but never names the sibling, so the differentiation is inferential rather than explicit.

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 'by code' phrasing implies you use this when you already know the plan's identifier, which is useful context, but there is no explicit when-to-use versus lago_list_plans or any statement about prerequisites or failure behavior.

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