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

Annotations already declare readOnlyHint, idempotentHint, and non-destructive behavior. The description adds valuable behavioral context beyond annotations: the tool is deterministic ('always the same answer'), returns a fixed set of card details, and does not perform variable lookups, which reinforces the closed-world and read-only nature.

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 description is a single, information-dense sentence that front-loads the core purpose ('the static LowerScript/SingleCare discount card') and then lists specific card components. While compact and without filler, the long enumerative structure could be slightly easier to parse if split, so it doesn't earn a perfect 5.

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 simple static tool with no output schema, the description gives a thorough list of what the response will contain, covering the return value context well. Combined with annotations that cover safety and idempotency, and a schema that documents the only parameter, nothing essential is missing for an agent to invoke 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?

The schema fully describes the single 'language' parameter with enum values and a default, so schema coverage is 100%. The description only references 'for a given language' without adding new meaning about the parameter, so it stays at the baseline for a fully documented 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?

The description clearly identifies the tool as returning 'the static LowerScript/SingleCare discount card' and enumerates its exact contents (BIN/PCN/GRP codes, usage instructions, links, support, compliance wording). It distinguishes itself from siblings by explicitly stating 'No lookup involved — always the same answer for a given language,' setting it apart from find_drug and get_prices.

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 description provides clear context for when to use the tool by emphasizing that it returns a static, predetermined answer and involves no lookup. It implicitly contrasts with lookup-based siblings like find_drug and get_prices, though it does not name them explicitly or give explicit when-not-to-use guidance.

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