Retrieve NOMIS codelists or a specific codelist definition for UK statistical data, providing the code sets needed to query ONS datasets.
List NOMIS codelists or return a codelist definition.
| Name | Required | Description | Default |
|---|---|---|---|
| tool | No | ||
| format | No | ||
| codelist | No |
| Name | Required | Description | Default |
|---|---|---|---|
| data | Yes | ||
| live | Yes | ||
| format | Yes | ||
| codelist | No |
Changes observed during successful MCP inspections.
v0.8.2Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, openWorldHint, and idempotentHint, so the safety profile is covered. The description adds no behavioral context beyond the core actions; it does not mention response behavior, codelist name requirements, or any other operational traits.
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 one short sentence with no filler. It front-loads the primary action and states the secondary action clearly, making it easy to scan.
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?
Despite strong annotations and an output schema, the description is not complete enough for an agent to confidently choose between list and definition behavior or to understand the 'format' parameter. It is a minimal description for a tool with three parameters and zero schema-level parameter documentation.
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 0%, yet the description does not explain the 'format' parameter or how 'codelist' selects a definition. It only hints that codelist relates to a definition, leaving parameter semantics largely to inference.
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 names a clear verb and resource: 'List NOMIS codelists' or 'return a codelist definition.' It identifies the domain sufficiently to distinguish it from sibling tools like nomis_datasets and nomis_concepts, though it does not explicitly name those alternatives.
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?
There is no guidance about when to use the list mode versus the definition mode, nor any mention of how this tool relates to sibling tools such as nomis_concepts or nomis_query. Usage context is only implied by the resource name.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.