Expand a UK postcode into every Royal Mail delivery point at that postcode — organisation, building, street, town, county, plus UDPRN, UPRN and rooftop coordinates for each address.
Cost: 1 credit per postcode, regardless of how many addresses come back;
an unknown/invalid postcode is refunded automatically.| Name | Required | Description | Default |
|---|---|---|---|
| postcode | Yes |
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations, the description discloses cost (1 credit), refund policy for invalid postcodes, and the type of data returned (UDPRN, UPRN, coordinates). This adequately conveys safe, read-only behavior. Could add rate limits or pagination if applicable.
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 with no wasted words. The first sentence states the verb and resource; the second provides cost details. Front-loaded and efficient.
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 one parameter and no output schema, the description covers purpose, return fields, cost, and refund policy. Could optionally detail output format, but not essential.
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 single parameter 'postcode' has 0% schema description coverage. The tool description explains its role and what the expansion yields, adding meaning beyond the bare schema. Could specify expected format (e.g., full UK postcode with space).
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 tool expands a UK postcode into delivery points, listing specific fields. It distinguishes from sibling tools like geocode_address or validate_address by explicitly focusing on UK postcode expansion.
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 explicit guidance on when to use this tool versus alternatives like enrich_us_ca_address or geocode_address. Usage is implied by the tool name and description, but lacks direct comparison or when-not scenarios.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
Add one secure layer between your agents and this server.
Most tools target distinct operations: validation (single/batch), geocoding, reverse geocoding, enrichment, UK postcode expansion, and account management. The main overlap is between enrich_us_ca_address and validate_address, which also includes an enrichment block for US/CA matches, potentially causing confusion about which to use.
All tool names follow a consistent verb_noun snake_case pattern (e.g., check_balance, expand_uk_postcode, validate_addresses_batch). The naming is uniform and predictable across the set.
8 tools is well within the ideal 3-15 range and appropriately scoped for a geocoding/validation API. Each tool serves a distinct function without unnecessary bloat, and the count reflects the complexity of the domain.
The core workflows—single and batch validation, forward and reverse geocoding, enrichment, and UK postcode expansion—are covered. Minor gaps include the lack of a batch geocoding tool and the redundant enrichment functionality already present in validate_address, but these do not create dead ends.