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

Annotations already declare readOnlyHint=true, so the safety profile is covered by structured data. The description adds only that results are 'paginated', which is useful but thin — it says nothing about page size defaults, ordering, filtering options, or rate limits behavior. With annotations carrying the read-only signal, this is adequate but not rich.

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 short sentences with the operation front-loaded and no wasted prose. The trailing 'Lago API: GET /customers' is mildly redundant with the first sentence but is a reasonable technical anchor rather than padding.

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 zero-required-parameter collection list with full schema coverage, no output schema, and a readOnlyHint, the description covers what is needed to invoke it correctly. Only marginal gaps remain around default ordering and result shape, which are not strictly necessary to make the call.

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 both parameters (page, per_page) are documented in the schema itself. The description's mention of 'paginated' corroborates but adds no syntax, defaults, or bounds beyond what the schema already provides, 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?

States a specific verb and resource ('List customers in Lago') plus the underlying endpoint 'GET /customers', so the operation is unambiguous. It does imply the plural collection scope versus the singular lago_get_customer sibling, but never names that distinction explicitly.

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 by the verb 'List' — the agent can infer this enumerates all customers rather than fetching one. There is no explicit statement about when to prefer this over lago_get_customer, lago_list_customer_subscriptions, or the analytics tools, and no conditions or exclusions are given.

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