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

Annotations already declare readOnlyHint=true, so safety is covered. The description adds real behavioral value beyond that: newest-first ordering, cursor-based pagination, and the payload shape (points_change signed +/-, customer-visible description, merchant-only internal_note). It does not cover rate limits or page-size defaults, which the schema handles.

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 sentences, front-loaded with the core purpose and scope before the parenthetical detail and pagination note. Dense and mostly waste-free, though the trailing 'Smile: GET /points_transactions' is implementation trivia of marginal value to an agent.

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 enumerates the returned fields and states ordering and pagination behavior. It omits any note on filtering behavior (e.g. what happens when customer_id is omitted) or result volumes, but it is sufficient to call the tool correctly.

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%, so limit, cursor, customer_id and updated_at_min are fully documented in the schema (including the Smile default of 50 and ISO 8601 format). The description only alludes to pagination via 'Cursor-paginated' and adds no syntax or semantics beyond the schema, so the baseline 3 is correct.

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 points transactions') and defines scope precisely as 'every earn, spend and manual adjustment', newest first, plus a concrete use case (a customer's full points history). It implicitly distinguishes itself from the singular sibling smile_get_points_transaction, but never names a sibling explicitly, so it falls just short of 5.

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 example ('a customer's full points history') implies when the tool is appropriate, and cursor pagination is disclosed, but there is no explicit when-to-use or when-not-to-use guidance and no routing to smile_get_points_transaction for single-record reads. Usage is only implied.

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