Crypto, web, finance and app data tools

Postal Code Lookup

postal_code

Places for a postal or ZIP code in about 60 countries: place names, state or region and coordinates. Use to validate addresses, fill forms or locate customers.

Tool call template

Replace each placeholder with a value matching the input schema. Only required parameters are included; add optional parameters as needed.

{
  "id": 1,
  "jsonrpc": "2.0",
  "method": "tools/call",
  "params": {
    "arguments": {
      "country": "<country>",
      "code": "<code>"
    },
    "name": "postal_code"
  }
}

Input Schema

Name	Required	Description	Default
`code`	Yes
`country`	Yes

Output Schema

Name	Required	Description	Default
`result`	Yes

Schema Changelog

Changes observed during successful MCP inspections.

AddedOct 22, 2026

TDQS

B3.4/5.0

Behavior3/5

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

With no annotations, the description carries the full burden and does disclose the 60-country coverage limit and the returned fields (place names, state/region, coordinates). It omits what happens for unknown/invalid codes, ambiguity handling, or any auth/rate constraints.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness4/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two compact sentences with no waste, leading with what the tool returns and following with use cases. Minor awkwardness in 'Places for a postal or ZIP code' but structure is front-loaded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists and the tool is simple (2 required params), so return values needn't be spelled out. However, the absence of parameter format guidance and not-found behavior leaves an agent without what it needs to call it confidently.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters2/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 0%, so both required params (country, code) depend entirely on the description, which only says 'postal or ZIP code' and never explains the expected country format (ISO code vs name) or code formatting. This does not compensate for the coverage gap.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb+resource (lookup places for a postal/ZIP code) plus scope (about 60 countries) and the fields returned. It differentiates itself implicitly from siblings like geocode and country_info by being code→place rather than address→coordinates, though it doesn't name an alternative.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines4/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

'Use to validate addresses, fill forms or locate customers' gives concrete when-to-use contexts. It stops short of exclusions or naming alternatives such as geocode, so an agent must still infer the boundary.

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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