lookup_postcodeConvenience: list the most recent HM Land Registry property sales for a single UK postcode (England & Wales). Returns sale price (£GBP), date, address, property type, tenure and new-build flag, newest sale first. Postcode must be UPPERCASE with a space, e.g. "SW1A 1AA".
| Name | Required | Description | Default |
|---|---|---|---|
| limit | No | Max records to return, 1-500. Default 25. | |
| postcode | Yes | UK postcode, UPPERCASE with a space, e.g. "WA2 8SN". |
Changes observed during successful MCP inspections.
Input schema / examplesAdded value: +[
+ {
+ "postcode": "WA2 8SN"
+ },
+ {
+ "limit": 50,
+ "postcode": "M1 1AD"
+ }
+]Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
Annotations already declare readOnlyHint, openWorldHint, idempotentHint, and destructiveHint false. The description adds valuable behavioral details: returns specific fields, newest first, and postcode formatting requirements. No contradictions.
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 that front-load the purpose and provide all necessary detail without excess. Every sentence earns its place.
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 tool with 2 parameters, no output schema, and no nested objects, the description covers purpose, input format, output fields, and ordering. It is fully adequate.
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%, but the description adds meaning beyond the schema: it specifies the postcode must be uppercase with a space, provides an example, and notes the default limit. This adds value for agent understanding.
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 states the verb 'list', the resource 'HM Land Registry property sales', and the scope 'single UK postcode (England & Wales)'. It distinguishes itself from sibling tools by being a focused, recent-sales lookup.
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 implies this is a convenience lookup for recent sales, but does not explicitly state when not to use it or mention alternatives. However, the context is clear enough for an agent to decide.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
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