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jagan-shanmugam

OpenStreetMap MCP Server

reverse_geocode

Convert geographic coordinates into a detailed address and location description, including street names, administrative boundaries, and contextual information for GPS data interpretation.

Instructions

Convert geographic coordinates to a detailed address and location description.

This tool takes a specific point on Earth (latitude and longitude) and returns comprehensive information about that location, including its address, nearby landmarks, administrative boundaries, and other contextual information. Useful for translating GPS coordinates into human-readable locations.

Args: latitude: The latitude coordinate (decimal degrees, WGS84) longitude: The longitude coordinate (decimal degrees, WGS84)

Returns: Detailed address and location information including: - Formatted address - Building, street, city, state, country - Administrative hierarchy - OSM metadata - Postal code and other relevant identifiers

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
latitudeYes
longitudeYes

Implementation Reference

  • The main MCP tool handler for 'reverse_geocode'. It extracts the OSM client from context and calls the helper method to perform the reverse geocoding.
    async def reverse_geocode(latitude: float, longitude: float, ctx: Context) -> Dict:
        """
        Convert geographic coordinates to a detailed address and location description.
        
        This tool takes a specific point on Earth (latitude and longitude) and returns 
        comprehensive information about that location, including its address, nearby landmarks,
        administrative boundaries, and other contextual information. Useful for translating
        GPS coordinates into human-readable locations.
        
        Args:
            latitude: The latitude coordinate (decimal degrees, WGS84)
            longitude: The longitude coordinate (decimal degrees, WGS84)
            
        Returns:
            Detailed address and location information including:
            - Formatted address
            - Building, street, city, state, country
            - Administrative hierarchy
            - OSM metadata
            - Postal code and other relevant identifiers
        """
        osm_client = ctx.request_context.lifespan_context.osm_client
        return await osm_client.reverse_geocode(latitude, longitude)
  • The OSMClient helper method that implements the core reverse geocoding logic by querying the Nominatim OSM API.
    async def reverse_geocode(self, lat: float, lon: float) -> Dict:
        """Reverse geocode coordinates to address"""
        if not self.session:
            raise RuntimeError("OSM client not connected")
        
        nominatim_url = "https://nominatim.openstreetmap.org/reverse"
        async with self.session.get(
            nominatim_url,
            params={
                "lat": lat,
                "lon": lon,
                "format": "json"
            },
            headers={"User-Agent": "OSM-MCP-Server/1.0"}
        ) as response:
            if response.status == 200:
                return await response.json()
            else:
                raise Exception(f"Failed to reverse geocode ({lat}, {lon}): {response.status}")
Behavior3/5

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

With no annotations provided, the description carries the full burden of behavioral disclosure. It describes the comprehensive nature of the return data and mentions the coordinate system (WGS84), which adds useful context. However, it doesn't disclose important behavioral traits like rate limits, authentication requirements, error conditions, or data source limitations that would be valuable for an agent.

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

Conciseness5/5

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

The description is well-structured with clear sections (purpose, usage context, Args, Returns) and every sentence earns its place. It's appropriately sized for a 2-parameter tool with no annotations, providing necessary information without redundancy or fluff. The information is front-loaded with the core purpose stated first.

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

Completeness4/5

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

Given the tool's moderate complexity, 2 parameters with 0% schema coverage, no annotations, and no output schema, the description does a good job covering the essentials. It explains the purpose, parameters, and return format in detail. The main gap is the lack of output schema, but the Returns section provides a comprehensive list of what to expect, making it reasonably complete for agent use.

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

Parameters5/5

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

The schema description coverage is 0%, so the description must fully compensate. It successfully adds significant meaning beyond the bare schema by explaining what latitude and longitude represent ('specific point on Earth', 'decimal degrees, WGS84'), their format, and their purpose in the geocoding process. The Args section provides clear semantic context for both parameters.

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

Purpose5/5

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

The description clearly states the tool's purpose with specific verb ('convert') and resource ('geographic coordinates'), and distinguishes it from siblings by focusing on reverse geocoding rather than forward geocoding (geocode_address) or other spatial analyses. The opening sentence directly explains what the tool does without restating the name.

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?

The description provides clear context about when to use this tool ('useful for translating GPS coordinates into human-readable locations'), which implicitly distinguishes it from forward geocoding and other spatial tools. However, it doesn't explicitly state when NOT to use it or name specific alternatives among the siblings.

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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