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

Annotations already establish that this is a safe, read-only, idempotent operation; the description adds useful behavioral context about data provenance and return semantics. It explains that values come from banks' own pages, are not counted in a plan, and are presented in the bank's own words, with per-£1,000 treatment for easy-access savers.

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?

The definition is compact and front-loads the resource scope before adding rate-basis caveats. It is somewhat dense and grammatically fragmentary, with a colon and parenthetical clause that slightly reduce immediate clarity.

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?

Given the simple no-parameter shape, read-only annotations, and absence of an output schema, the description supplies enough context about what the returned entries represent and how their values are framed. The main gap is the lack of usage guidance relative to sibling offer tools.

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?

This tool takes zero parameters, so there are no parameter meanings for the description to compensate for. The baseline for a no-parameter tool is 4, and nothing in the description introduces parameter-related ambiguity.

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?

The description identifies the exact resource and scope: savers and cashback sourced from banks' own pages, including how payouts are represented. It does not explicitly state the list action or differentiate from named siblings, leaving the tool name to supply the verb.

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 'never counted in a plan' hints at an exclusion, but there is no explicit guidance on when to use this tool instead of check_offers, get_offer, list_offers, or list_changes. An agent must infer selection from the resource name alone.

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