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

readOnlyHint=true already tells the agent this is a safe read, so the bar is lower. The description adds useful context by disclosing that the response includes the product's reward, which is not implied by the annotations or schema. It says nothing about behavior on a missing/invalid ID, but for a simple read that gap is minor.

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 compact sentences, zero filler. The core action and scope are front-loaded, and the trailing 'Smile: GET /points_products/{id}' endpoint reference is a single low-cost clause.

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 one-parameter read tool with annotations covering its safety profile and no output schema, the description covers purpose, lookup key, and the notable return element (the reward). Only the absence of any error/not-found behavior or cross-reference to siblings keeps it short of complete.

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 single parameter (points_product_id) is fully documented in the schema with type and bounds. The description only restates 'by ID' and adds no format or constraint detail beyond the schema, 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 ('Fetch one points product ... by ID') and clarifies the domain concept ('a way to redeem points'). The word 'one' plus the ID qualifier distinguishes it from the sibling smile_list_points_products without either schema being opened.

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 ID' phrasing implies this is the lookup for a known product ID, which is implicit usage guidance. However, it never states when to use this versus smile_list_points_products or smile_purchase_points_product, nor any prerequisite such as needing a valid ID first.

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