Retrieve all GoodRx drugs for one directory letter, including each drug's price-page slug and drug-information URL.
List GoodRx drugs by letter. Returns every drug in one letter of GoodRx's A-Z drug directory, with the price-page slug and drug-information URL.
| Name | Required | Description | Default |
|---|---|---|---|
| letter | Yes | Directory letter |
Changes observed during successful MCP inspections.
v1.17.9Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description carries the full burden. It usefully discloses the return payload (price-page slug and drug-information URL) and implies a read-only enumeration, but says nothing about authentication, rate limits, pagination, or the volume of results a full letter can return.
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 action and backed by one sentence on the return shape. Every clause carries information and there is no filler.
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 single-parameter enumeration tool with an enum-constrained input and no output schema, the description covers purpose and return fields adequately. It falls slightly short on result volume/pagination and on routing versus other goodrx tools, but nothing critical is missing for a correct call.
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 param is an a-z enum documented as 'Directory letter', so the schema does the heavy lifting. The description reinforces the letter-based semantics ('one letter of GoodRx's A-Z drug directory') but adds no format or edge-case detail beyond it.
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 GoodRx drugs') plus the organizing axis ('by letter'), which is concrete enough for an agent to act on. It does not, however, distinguish itself from the many goodrx sibling tools (goodrx_drug_info, goodrx_drug_guides, goodrx_drug_options), so the A-Z directory framing is the main differentiator rather than an explicit comparison.
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?
No when-to-use guidance and no named alternatives are given. The description never says whether this is for browsing/enumeration versus looking up a specific drug (which other goodrx tools likely handle), leaving the agent to infer the selection condition.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.