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

Annotations already establish read-only, idempotent, closed-world behavior, so the bar is lower. The description adds genuinely useful context beyond that: the exact content returned, and that each fact carries the date it was last verified at the brand's own site, which signals freshness/data provenance.

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?

A single sentence that front-loads the scope and then lists the payload contents. It is dense but every clause carries information; only mild awkwardness in the 'One UK loyalty scheme CardPoints covers' construction.

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 does the work of telling the agent what comes back and that values are dated, which is sufficient for a simple single-parameter read tool. Only the absence of explicit routing to siblings keeps it from full marks.

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 'scheme' parameter already has examples like 'Boots Advantage Card' and 'Nectar'. The description only reinforces the one-scheme scope, adding little syntactic or interpretive meaning 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 clearly that it returns the details of a single UK loyalty scheme and enumerates what is covered (points value, earning rate, expiry, current offers). It's clear but the verb is implicit ('covers') and it never names the sibling tools, so differentiation is left to inference.

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 phrase 'One UK loyalty scheme' implies a single-scheme lookup as opposed to the comparison/point-finding siblings, but there is no explicit when-to-use or when-to-prefer-an-alternative guidance. Usage is only inferable from the scope wording.

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