epsg-mcp
The EPSG MCP server provides specialized knowledge and decision support for Coordinate Reference Systems (CRS) worldwide, helping users make informed choices for mapping, surveying, and spatial data projects.
Core Capabilities:
CRS Search & Information: Search by EPSG code, name, region, or prefecture with filtering by type; get detailed information on datum, projection, area of use, and accuracy
Regional CRS Management: List CRS by region (Japan, Global) with purpose-specific recommendations, including Japan's Plane Rectangular CS Zones I-XIX
CRS Recommendation: Get optimal CRS recommendations based on purpose (web mapping, surveying, distance/area calculation, navigation, data exchange, storage, visualization) and location, with multi-zone support for regions like Hokkaido and Okinawa
CRS Validation: Verify if a CRS is appropriate for specific purposes and locations, detecting issues like deprecated usage, distortion problems, zone mismatches, and GeoJSON incompatibility
Transformation Planning: Find optimal multi-step transformation paths (up to 4 steps) between CRS using BFS graph search, with accuracy information, reverse transformation support, and warnings about cumulative errors
CRS Comparison: Compare two CRS across 7 perspectives: datum, projection method, area of use, accuracy, distortion characteristics, compatibility (GIS/Web/CAD/GPS), and use case suitability
Best Practices Guidance: Access guidance on 10 topics including surveying in Japan, web mapping, data exchange, coordinate storage, mobile GPS, cross-border data, historical data handling, GIS integration, precision requirements, and projection selection
Troubleshooting: Diagnose CRS-related problems like coordinate shifts (cm to km scale), calculation errors, display issues, and transformation failures with diagnostic steps and solutions
Coverage:
Japan: JGD2011, Plane Rectangular CS Zones I-XIX, legacy Tokyo Datum and JGD2000
United States: NAD83, NAD83(2011), State Plane systems, and specialized projections
United Kingdom: OSGB36, ETRS89, British National Grid, Irish Transverse Mercator
Global: WGS84, Web Mercator, UTM zones
Extensible: Country pack system for adding new regions, with automatic UTM fallback for areas without specific packs
Optional: Full EPSG registry (10,000+ CRS) via SQLite database
Additional Features:
Offline Operation: Works without external API dependencies using local database
Internationalization: Tools and descriptions are internationalized for use by AI agents in multiple languages
EPSG MCP Server
An MCP server that provides specialized knowledge and decision support for Coordinate Reference Systems (CRS) worldwide.
Global coverage through a 3-layer fallback:
Country Packs (Japan, US State Plane, UK National Grid, etc.) for expert-level recommendations
Automatic UTM zone calculation when no pack is available
Safe defaults (WGS84 / Web Mercator) as the final fallback
Coordinate transformation execution is delegated to mcp-server-proj, focusing on knowledge provision and decision support.
Features
CRS Search: Search CRS by EPSG code, name, region, or prefecture
Detailed Information: Get detailed information on geodetic datum, projection method, area of use, accuracy characteristics, and more
Regional Listings: List CRS available in Japan/Global with purpose-specific recommendations
CRS Recommendation: Recommend the optimal CRS for each purpose and location (with multi-zone support for Hokkaido and Okinawa)
Usage Validation: Verify the validity of CRS selection and present issues with suggestions for improvement
Transformation Routing: Propose optimal transformation paths using BFS graph search (with reverse transformation support)
CRS Comparison: Compare CRS from 7 perspectives (datum, projection, accuracy, distortion, compatibility, etc.)
Best Practices: CRS usage guidance on 10 topics (surveying, web mapping, data exchange, etc.)
Troubleshooting: Diagnose CRS problems by symptoms (coordinate shifts, calculation errors, etc.)
Country Pack System: Extensible regional expertise (Japan, US, UK available; easily add more)
Offline Operation: Local database requires no external API
Internationalized: Tool definitions and parameter descriptions in English (usable by AI agents in any language)
Graceful Degradation: Works anywhere via UTM fallback even without region-specific packs
Related MCP server: chuk-mcp-geocoder
Installation
npm install @shuji-bonji/epsg-mcpOr run directly:
npx @shuji-bonji/epsg-mcpUsage
Claude Desktop
Add to claude_desktop_config.json:
{
"mcpServers": {
"epsg": {
"command": "npx",
"args": ["@shuji-bonji/epsg-mcp"]
}
}
}Enabling Additional Country Packs
By default, only the Japan pack is loaded. To enable additional packs (e.g., US, UK), set the EPSG_PACKS environment variable:
{
"mcpServers": {
"epsg": {
"command": "npx",
"args": ["@shuji-bonji/epsg-mcp"],
"env": {
"EPSG_PACKS": "jp,us,uk"
}
}
}
}Available packs: jp (Japan), us (United States), uk/gb (United Kingdom)
Language Settings
By default, output is in English. To get Japanese output, set the EPSG_LANG environment variable:
{
"mcpServers": {
"epsg": {
"command": "npx",
"args": ["@shuji-bonji/epsg-mcp"],
"env": {
"EPSG_LANG": "ja"
}
}
}
}MCP Inspector
npx @modelcontextprotocol/inspector npx @shuji-bonji/epsg-mcpTools
search_crs
Search CRS by keyword.
// Input
{
query: string; // Search keyword (e.g., "JGD2011", "4326", "Tokyo")
type?: "geographic" | "projected" | "compound" | "vertical" | "engineering";
region?: "Japan" | "Global";
limit?: number; // Default: 10, max: 100
}
// Output
{
results: CrsInfo[];
totalCount: number;
}Usage Examples:
"Search for CRS related to JGD2011"
"Find projected coordinate systems available in Tokyo"
"Get information about EPSG code 6677"
get_crs_detail
Get detailed CRS information by EPSG code.
// Input
{
code: string; // "EPSG:6677" or "6677"
}
// Output
{
code: string;
name: string;
type: CrsType;
datum?: DatumInfo;
projection?: ProjectionInfo;
areaOfUse: AreaOfUse;
accuracy?: AccuracyInfo;
remarks?: string;
useCases?: string[];
// ...
}Usage Examples:
"Tell me the details of EPSG:6677"
"What are the characteristics of Web Mercator (3857)?"
list_crs_by_region
Get available CRS list and recommendations by region.
// Input
{
region: "Japan" | "Global";
type?: CrsType;
includeDeprecated?: boolean; // Default: false
}
// Output
{
region: string;
crsList: CrsInfo[];
recommendedFor: {
general: string;
survey: string;
webMapping: string;
};
}Usage Examples:
"List CRS available in Japan"
"What global geographic coordinate systems are there?"
recommend_crs
Recommend optimal CRS based on purpose and location.
// Input
{
purpose: "web_mapping" | "distance_calculation" | "area_calculation" |
"survey" | "navigation" | "data_exchange" | "data_storage" | "visualization";
location: {
country?: string; // "Japan" | "Global"
region?: string; // "Kanto", "Hokkaido", "Main Island", "Sakishima", etc.
prefecture?: string; // "Tokyo", "Hokkaido", etc.
city?: string; // "Sapporo", "Naha", etc. (for multi-zone support)
boundingBox?: BoundingBox;
centerPoint?: { lat: number; lng: number };
};
requirements?: {
accuracy?: "high" | "medium" | "low";
distortionTolerance?: "minimal" | "moderate" | "flexible";
interoperability?: string[]; // e.g., ["GIS", "CAD", "Web"]
};
}
// Output
{
primary: RecommendedCrs; // Recommended CRS (with score, pros, cons)
alternatives: RecommendedCrs[];
reasoning: string;
warnings?: string[]; // Warnings for areas spanning multiple zones
}Usage Examples:
"What's the best CRS for distance calculation around Tokyo?"
"What CRS should I use for surveying in Sapporo, Hokkaido?"
"I want to display a map of all Japan in a web app"
validate_crs_usage
Validate whether a specified CRS is appropriate for a specific purpose and location.
// Input
{
crs: string; // "EPSG:3857" or "3857"
purpose: Purpose; // Same as recommend_crs
location: LocationSpec; // Same as recommend_crs
}
// Output
{
isValid: boolean;
score: number; // Suitability 0-100
issues: ValidationIssue[]; // List of issues
suggestions: string[]; // Improvement suggestions
betterAlternatives?: RecommendedCrs[]; // Alternatives when score is low
}Detected Issues Examples:
DEPRECATED_CRS: Using deprecated CRSAREA_DISTORTION: Area calculation with Web MercatorZONE_MISMATCH: Using Zone I (for Nagasaki) in TokyoGEOJSON_INCOMPATIBLE: Outputting GeoJSON with projected CRS
Usage Examples:
"Is it OK to use Web Mercator for area calculation in Hokkaido?"
"Any issues with storing survey data in Japan using EPSG:4326?"
suggest_transformation
Suggest optimal transformation path between two CRS.
// Input
{
sourceCrs: string; // "EPSG:4301" or "4301"
targetCrs: string; // "EPSG:6668" or "6668"
location?: {
country?: string;
prefecture?: string;
boundingBox?: BoundingBox;
};
}
// Output
{
directPath: TransformationPath | null; // Direct transformation path
viaPaths: TransformationPath[]; // Indirect transformation paths
recommended: TransformationPath; // Recommended path
warnings: string[];
}TransformationPath:
steps: Array of transformation steps (from, to, method, accuracy, isReverse)totalAccuracy: Overall accuracycomplexity: "simple" | "moderate" | "complex"
Features:
BFS graph search for paths up to 4 steps
Automatic consideration of reverse transformations (reversible: true)
Warnings when using deprecated CRS (Tokyo Datum, JGD2000)
Accuracy warnings for large area data transformation
Usage Examples:
"How to transform from Tokyo Datum to JGD2011?"
"Show me the transformation path from WGS84 to Web Mercator"
compare_crs
Compare two CRS from various perspectives.
// Input
{
crs1: string; // "EPSG:4326" or "4326"
crs2: string; // "EPSG:6668" or "6668"
aspects?: ComparisonAspect[]; // Specify comparison aspects (all if omitted)
}
// ComparisonAspect
"datum" | "projection" | "area_of_use" | "accuracy" | "distortion" | "compatibility" | "use_cases"
// Output
{
comparison: ComparisonResult[]; // Comparison results for each aspect
summary: string; // Summary
recommendation: string; // Recommendation
transformationNote?: string; // Notes on transformation
}Comparison Aspects:
datum: Datum comparison (e.g., WGS84 vs JGD2011 are practically identical)projection: Projection comparisonarea_of_use: Area of use comparisonaccuracy: Accuracy characteristics comparisondistortion: Distortion characteristics comparisoncompatibility: GIS/Web/CAD/GPS compatibility comparisonuse_cases: Use case suitability comparison (score-based)
Usage Examples:
"What's the difference between WGS84 and JGD2011?"
"Compare Web Mercator and geographic CRS"
"Compare JGD2000 and JGD2011 from the datum perspective"
get_best_practices
Get best practices for CRS usage.
// Input
{
topic: "japan_survey" | "web_mapping" | "data_exchange" | "coordinate_storage" |
"mobile_gps" | "cross_border" | "historical_data" | "gis_integration" |
"precision_requirements" | "projection_selection";
context?: string; // Additional context (optional, max 500 characters)
}
// Output
{
topic: string;
description: string;
practices: Practice[]; // Recommended practices
commonMistakes: Mistake[]; // Common mistakes
relatedTopics: string[]; // Related topics
references: Reference[]; // Reference materials
}Practice:
title: Practice namedescription: Descriptionpriority: "must" | "should" | "may"rationale: Rationaleexample?: Concrete example
Usage Examples:
"What are the best practices for surveying in Japan?"
"How to choose coordinate systems when creating web maps"
"What to watch out for when exchanging data in GeoJSON"
troubleshoot
Troubleshoot CRS-related problems.
// Input
{
symptom: string; // Symptom (2-500 characters)
context?: {
sourceCrs?: string; // Source CRS
targetCrs?: string; // Target CRS
location?: string; // Target region
tool?: string; // Tool being used
magnitude?: string; // Magnitude of shift
};
}
// Output
{
matchedSymptom: string; // Matched symptom category
possibleCauses: Cause[]; // Possible causes (with likelihood)
diagnosticSteps: DiagnosticStep[]; // Diagnostic steps
suggestedSolutions: Solution[]; // Solutions
relatedBestPractices: string[]; // Related best practices
confidence: "high" | "medium" | "low"; // Diagnosis confidence
}Supported Symptoms:
Coordinates shift by hundreds of meters to kilometers (Tokyo Datum issues, etc.)
Coordinates shift by 1-several meters (transformation accuracy limits, etc.)
Coordinates shift by centimeters to tens of centimeters (WGS84/JGD2011 difference, etc.)
Area/distance calculations are incorrect (Web Mercator distortion, etc.)
Data doesn't display (CRS mismatch, etc.)
Coordinate transformation errors (unregistered parameters, etc.)
Usage Examples:
"Coordinates are off by 400m"
"Area calculation results are wrong"
"Old data and new data don't align"
Supported CRS
Japan (JGD2011)
EPSG | Name | Usage |
6668 | JGD2011 | Geographic CRS (reference) |
6669-6687 | Japan Plane Rectangular CS I-XIX | Surveying, large-scale maps |
4612 | JGD2000 | Legacy (deprecated) |
United States (NAD83)
EPSG | Name | Usage |
4269 | NAD83 | Geographic CRS (standard) |
6318 | NAD83(2011) | Latest realization |
5070 | NAD83 / Conus Albers | Area calculations |
2229 | NAD83 / California zone 5 | State Plane example |
2263 | NAD83 / New York Long Island | State Plane example |
United Kingdom (OSGB36/ETRS89)
EPSG | Name | Usage |
4277 | OSGB36 | Geographic CRS (legacy) |
4258 | ETRS89 | Geographic CRS (modern) |
27700 | British National Grid | Surveying, mapping |
2157 | Irish Transverse Mercator | Northern Ireland |
Global
EPSG | Name | Usage |
4326 | WGS 84 | GPS/GeoJSON standard |
3857 | Web Mercator | Web map display |
326xx | UTM zones | Distance/area calculation |
Extended CRS Support (Optional)
By default, this server provides CRS data for Japan and major global systems. For access to the complete EPSG registry (10,000+ CRS), you can optionally enable SQLite support.
Setup
Download EPSG Database
# Using the built-in script
npm run epsg:download-db
# Or specify a custom path
npx tsx scripts/download-epsg-db.ts ./path/to/epsg.dbInstall sql.js (only if
npm installdid not install it)
sql.js is already listed in optionalDependencies, so it is normally installed automatically when you run npm install @shuji-bonji/epsg-mcp. You only need this step if the optional dependency was skipped (e.g., by --no-optional):
npm install sql.jsConfigure Environment
Set the EPSG_DB_PATH environment variable:
export EPSG_DB_PATH="/path/to/epsg.db"Or configure in Claude Desktop's claude_desktop_config.json:
{
"mcpServers": {
"epsg": {
"command": "npx",
"args": ["@shuji-bonji/epsg-mcp"],
"env": {
"EPSG_DB_PATH": "/path/to/epsg.db"
}
}
}
}Data Source
The EPSG database is provided by PROJ, which redistributes the IOGP EPSG Geodetic Parameter Dataset. Please refer to the EPSG Terms of Use for licensing information.
Development
# Install dependencies
npm install
# Build
npm run build
# Test
npm test
# Watch mode
npm run test:watchDocumentation
Usage Examples - Practical scenarios showing how EPSG MCP helps with CRS decisions
Creating Country Packs - Guide for adding new country/region support
Roadmap
Phase 1 ✅: search_crs, get_crs_detail, list_crs_by_region
Phase 2 ✅: recommend_crs, validate_crs_usage
Phase 3 ✅: suggest_transformation, compare_crs
Phase 4 ✅: get_best_practices, troubleshoot
Phase 5 ✅: Internationalization & multi-region support (Country Pack system, UTM fallback, optional SQLite backend, JP/US/UK packs)
Related Projects
mcp-server-proj - MCP server for coordinate transformation execution
EPSG.io - EPSG coordinate system database
License
MIT License - see LICENSE for details.
Available Tools
9 toolscompare_crsA
Compare two CRS from various perspectives. Compares datum, projection method, area of use, accuracy, distortion characteristics, compatibility, and use case suitability. Explains which is better suited for specific purposes.
| Name | Required | Description | Default |
|---|---|---|---|
| crs1 | Yes | First EPSG code to compare (e.g., "EPSG:4326" or "4326") | |
| crs2 | Yes | Second EPSG code to compare (e.g., "EPSG:6668" or "6668") | |
| aspects | No | Comparison aspects (all if omitted). accuracy: precision, area_of_use: coverage, distortion: distortion properties, compatibility: interoperability, use_cases: suitability, datum: geodetic datum, projection: projection method |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden of behavioral disclosure. It describes what aspects are compared but doesn't cover behavioral traits such as performance characteristics, error handling, or output format. For a tool with no annotations, this leaves significant gaps in understanding how the tool behaves operationally.
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 front-loaded with the core purpose and efficiently lists comparison aspects in a single sentence, followed by a second sentence on suitability explanation. It avoids redundancy, though it could be slightly more concise by integrating the two sentences.
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?
Given no annotations and no output schema, the description adequately covers the tool's purpose and parameters but lacks details on behavioral traits and output format. For a comparison tool with 3 parameters and 100% schema coverage, it's minimally viable but incomplete in providing full operational context.
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 100%, so the schema already documents all parameters thoroughly. The description adds value by listing the comparison aspects (e.g., datum, projection method) that map to the 'aspects' parameter, but doesn't provide additional semantic context beyond what's in the schema. Baseline 3 is appropriate when schema does the heavy lifting.
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 'compare' and the resource 'two CRS', specifying the comparison covers multiple perspectives including datum, projection method, area of use, accuracy, distortion characteristics, compatibility, and use case suitability. It distinguishes from siblings like get_crs_detail (single CRS detail) and recommend_crs (recommendations rather than comparison).
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 when to use this tool by stating it 'explains which is better suited for specific purposes,' suggesting it's for comparative analysis. However, it doesn't explicitly state when not to use it or name alternatives like get_crs_detail for single CRS information or recommend_crs for recommendations without detailed comparison.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_best_practicesC
Get CRS best practices for specific topics. Covers surveying in Japan, web mapping, data exchange, coordinate storage, mobile GPS, cross-border data, historical data, GIS integration, precision requirements, and projection selection. Provides recommended practices, common mistakes, and reference materials.
| Name | Required | Description | Default |
|---|---|---|---|
| topic | Yes | Best practice topic. japan_survey: surveying in Japan, web_mapping: web map creation, data_exchange: interoperability, coordinate_storage: archival, mobile_gps: mobile GPS apps, cross_border: cross-border data, historical_data: legacy data, gis_integration: GIS system integration, precision_requirements: accuracy specs, projection_selection: choosing projections | |
| context | No | Additional context information (optional, max 500 chars) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries the full burden. It mentions what the tool provides ('recommended practices, common mistakes, and reference materials') but lacks behavioral details such as response format, error handling, rate limits, or authentication requirements. For a tool with no annotations, this leaves significant gaps in understanding how it behaves.
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 appropriately sized and front-loaded with the core purpose. It efficiently lists topics and what's provided in a single sentence. There's no wasted text, though it could be slightly more structured for clarity.
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?
Given no annotations and no output schema, the description is moderately complete for a read-only tool. It covers the purpose and topics but lacks details on return values, error cases, or operational constraints. It's adequate but has clear gaps in behavioral context.
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 100%, so the schema already documents both parameters thoroughly. The description adds minimal value beyond the schema by listing topic areas but doesn't provide additional semantics like parameter interactions or usage examples. Baseline 3 is appropriate as the schema does the heavy lifting.
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's purpose: 'Get CRS best practices for specific topics' with a specific verb ('Get') and resource ('CRS best practices'). It lists the topics covered, which helps distinguish it from sibling tools like 'get_crs_detail' or 'recommend_crs', though it doesn't explicitly differentiate from them. The purpose is specific but lacks direct sibling comparison.
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 provides no guidance on when to use this tool versus alternatives. It lists topics covered but doesn't mention when to choose it over sibling tools like 'recommend_crs' or 'troubleshoot'. There are no explicit usage scenarios, prerequisites, or exclusions provided.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
get_crs_detailC
Get detailed information for a specific EPSG code. Includes datum, projection method, area of use, accuracy characteristics, and intended use cases.
| Name | Required | Description | Default |
|---|---|---|---|
| code | Yes | EPSG code (e.g., "EPSG:6677" or "6677") |
TDQS
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 what information is returned but doesn't cover critical aspects like whether this is a read-only operation, potential error conditions (e.g., invalid codes), performance characteristics, or authentication needs. For a tool with zero annotation coverage, this is a significant gap in transparency.
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 appropriately concise and front-loaded, stating the core purpose in the first sentence and listing included details efficiently. Every sentence adds value by specifying the scope of information retrieved. Minor improvement could be made by structuring it more explicitly, but it's largely waste-free.
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?
Given the tool's low complexity (single parameter, no output schema, no annotations), the description is minimally adequate. It covers what the tool does but lacks completeness in behavioral aspects and usage context. For a read operation with good schema coverage, this is acceptable but leaves room for improvement in guiding the agent effectively.
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 description adds no parameter-specific information beyond what the input schema provides. Since schema description coverage is 100% (the 'code' parameter is well-documented in the schema), the baseline score is 3. The description doesn't compensate with additional context like format examples or usage tips, but it doesn't need to given the schema's completeness.
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's purpose with a specific verb ('Get detailed information') and resource ('for a specific EPSG code'), and lists the types of information included (datum, projection method, area of use, accuracy characteristics, intended use cases). However, it doesn't explicitly differentiate from sibling tools like 'search_crs' or 'list_crs_by_region' that might also retrieve CRS information, which prevents a perfect score.
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 provides no guidance on when to use this tool versus alternatives. It doesn't mention prerequisites, exclusions, or compare it to sibling tools such as 'search_crs' for broader queries or 'validate_crs_usage' for validation purposes. This lack of contextual usage information leaves the agent without clear direction.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
list_crs_by_regionB
Get available CRS list for a region with purpose-based recommendations. Japan includes Plane Rectangular CS (Zones I-XIX), Global includes WGS84 and UTM zones.
| Name | Required | Description | Default |
|---|---|---|---|
| region | Yes | Region name ("Japan" or "Global") | |
| type | No | Filter by CRS type | |
| includeDeprecated | No | Include deprecated CRS (default: false) |
TDQS
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 mentions 'purpose-based recommendations' which suggests some advisory functionality, but doesn't clarify whether this is a read-only operation, what permissions might be required, how results are structured, or any rate limits. For a tool with 3 parameters and no annotation coverage, this leaves significant behavioral gaps.
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 efficiently structured in two sentences. The first sentence states the core purpose, and the second provides helpful region-specific examples. There's no wasted text, and the information is front-loaded with the main functionality stated first.
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?
Given the tool has 3 parameters with 100% schema coverage but no annotations and no output schema, the description provides adequate basic context about what the tool does and some region examples. However, for a tool that apparently provides 'purpose-based recommendations' (suggesting some complexity), the description doesn't explain what form these recommendations take or how results are structured, leaving gaps in completeness.
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 100%, so the schema already documents all parameters thoroughly. The description adds some context by mentioning specific CRS examples for Japan and Global regions, which relates to the 'region' parameter, but doesn't provide additional semantic meaning beyond what's in the schema descriptions. This meets the baseline for high schema coverage.
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's purpose: 'Get available CRS list for a region with purpose-based recommendations.' It specifies the verb ('Get'), resource ('CRS list'), and scope ('for a region'), and provides examples for Japan and Global regions. However, it doesn't explicitly differentiate from sibling tools like 'search_crs' or 'recommend_crs' in terms of functionality boundaries.
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 usage context by mentioning 'purpose-based recommendations' and providing region-specific examples (Japan includes Plane Rectangular CS, Global includes WGS84 and UTM zones). However, it doesn't explicitly state when to use this tool versus alternatives like 'search_crs' or 'recommend_crs', nor does it mention any exclusions or prerequisites for usage.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
recommend_crsB
Recommend the optimal CRS based on purpose and location. Supports web mapping, distance/area calculation, surveying, navigation, data exchange, etc. Full support for Japan Plane Rectangular CS (Zones I-XIX) including multi-zone regions like Hokkaido and Okinawa.
| Name | Required | Description | Default |
|---|---|---|---|
| purpose | Yes | Intended use (web_mapping: web map display, distance_calculation: distance calc, area_calculation: area calc, survey: surveying, navigation: GPS/navigation, data_exchange: interoperability, data_storage: archival, visualization: display) | |
| location | Yes | Target location specification | |
| requirements | No | Additional requirements |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries full burden for behavioral disclosure. It mentions support for specific use cases and regional systems, but does not disclose critical traits such as whether this is a read-only operation, if it requires authentication, potential rate limits, or what the output format might be (e.g., a recommended CRS code or detailed analysis). For a recommendation tool with complex inputs, this is a significant gap in transparency.
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 appropriately sized with two sentences: the first states the core purpose and use cases, the second adds regional specificity. It is front-loaded with the main function, and each sentence adds value (e.g., listing supported purposes and Japan-specific zones). Minor room for improvement in structuring the use-case list more clearly, but overall efficient with zero waste.
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?
Given the tool's complexity (3 parameters with nested objects, no output schema, and no annotations), the description is incomplete. It lacks information on output format (what the recommendation looks like), behavioral constraints (e.g., is it deterministic or heuristic-based), and how to interpret results relative to sibling tools. Without annotations or output schema, the description should compensate more to guide the agent effectively.
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 100%, so the schema already documents all parameters thoroughly. The description adds no specific parameter semantics beyond what's in the schema—it does not explain how 'purpose' influences recommendations, how 'location' details are prioritized, or how 'requirements' affect the output. Baseline 3 is appropriate as the schema does the heavy lifting, but the description fails to add meaningful context.
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's purpose: 'Recommend the optimal CRS based on purpose and location.' It specifies the verb ('Recommend') and resource ('optimal CRS'), and distinguishes from siblings by focusing on recommendation rather than comparison, listing, validation, or other operations. The mention of specific use cases (web mapping, distance calculation, etc.) and regional support (Japan Plane Rectangular CS) further clarifies scope.
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 usage through examples ('Supports web mapping, distance/area calculation...') and regional specificity ('Full support for Japan Plane Rectangular CS...'), suggesting it's for CRS selection tasks. However, it lacks explicit guidance on when to use this tool versus alternatives like 'compare_crs' or 'search_crs', and does not mention prerequisites or exclusions, leaving the agent to infer context from the input schema.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
search_crsA
Search EPSG Coordinate Reference Systems (CRS) by keyword. Searchable by EPSG code, name, region name, or prefecture name. Covers Japanese JGD2011 CRS family, global WGS84, Web Mercator, and more.
| Name | Required | Description | Default |
|---|---|---|---|
| query | Yes | Search keyword (e.g., "JGD2011", "4326", "Tokyo", "plane rectangular") | |
| type | No | Filter by CRS type (geographic: lat/lon, projected: x/y meters) | |
| region | No | Filter by region ("Japan" or "Global") | |
| limit | No | Maximum number of results (default: 10, max: 100) |
TDQS
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 adds useful context about search scope (covers Japanese JGD2011, global WGS84, Web Mercator) and searchable fields, but does not disclose critical behavioral traits such as pagination behavior, rate limits, authentication needs, or what happens with no results. The description provides some operational context but leaves gaps in behavioral transparency.
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 appropriately sized and front-loaded with the core purpose in the first sentence. Every sentence adds value: the first defines the tool, the second specifies searchable fields, and the third provides coverage context. There is zero waste, and the structure efficiently conveys essential information.
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?
Given the tool's moderate complexity (4 parameters, no output schema, no annotations), the description is reasonably complete. It covers purpose, usage context, and parameter hints, but lacks details on output format, error handling, or behavioral constraints. With no output schema, the description could benefit from mentioning what results look like, but it adequately supports basic tool selection and invocation.
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 100%, so the schema already documents all parameters thoroughly. The description adds marginal value by mentioning searchable fields (EPSG code, name, region name, prefecture name) and coverage examples, but does not provide additional syntax, format details, or usage examples beyond what the schema provides. This meets the baseline for high schema coverage.
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 ('Search') and resource ('EPSG Coordinate Reference Systems (CRS)'), and distinguishes from siblings by specifying keyword-based search functionality. It explicitly mentions what can be searched (EPSG code, name, region name, prefecture name) and provides coverage examples (JGD2011, WGS84, Web Mercator), making the purpose specific and differentiated.
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 provides clear context for when to use this tool (searching CRS by keyword) and implies alternatives by mentioning coverage of specific CRS families, but does not explicitly name sibling tools like 'list_crs_by_region' or 'get_crs_detail' as alternatives. It gives guidance on searchable fields but lacks explicit when-not-to-use statements or direct comparisons to other tools.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
suggest_transformationA
Suggest transformation paths between two CRS. Covers Tokyo Datum to JGD2011, WGS84 to Plane Rectangular CS, etc. Searches multi-step paths, provides accuracy info, and warns about cumulative errors.
| Name | Required | Description | Default |
|---|---|---|---|
| sourceCrs | Yes | Source EPSG code (e.g., "EPSG:4301" or "4301") | |
| targetCrs | Yes | Target EPSG code (e.g., "EPSG:6668" or "6668") | |
| location | No | Location of data being transformed (optional, for accuracy improvement) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries full burden. It discloses key behavioral traits: it searches multi-step paths, provides accuracy information, and warns about cumulative errors. However, it doesn't mention authentication requirements, rate limits, error handling, or what format the suggestions come in. The behavioral disclosure is adequate but incomplete for a tool with complex transformation logic.
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 perfectly front-loaded with the core purpose in the first sentence, followed by specific examples and additional capabilities. Every sentence adds value: the examples clarify scope, and the subsequent sentences explain the search behavior and output characteristics. Zero wasted words.
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 tool with 3 parameters (including a complex nested object), no annotations, and no output schema, the description provides good purpose and usage context but lacks details about the output format, error conditions, or performance characteristics. Given the complexity of coordinate reference system transformations, more behavioral context would be helpful despite the excellent parameter documentation in the schema.
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 100%, so the schema already documents all parameters thoroughly. The description adds meaningful context by explaining that the tool handles specific transformation examples (Tokyo Datum to JGD2011, WGS84 to Plane Rectangular CS) and that location is 'for accuracy improvement', which provides valuable semantic context beyond the schema's technical descriptions.
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's purpose with specific verbs ('suggest transformation paths', 'searches multi-step paths', 'provides accuracy info', 'warns about cumulative errors') and resources ('between two CRS'). It explicitly distinguishes its functionality from siblings by focusing on transformation pathfinding rather than comparison, listing, validation, or troubleshooting.
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 provides clear context for when to use this tool ('between two CRS' with examples like 'Tokyo Datum to JGD2011'), but doesn't explicitly state when not to use it or name specific alternatives among the sibling tools. The examples help guide usage, but no explicit exclusions or comparisons to siblings are provided.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
troubleshootB
Troubleshoot CRS-related problems. Diagnoses coordinate shifts (cm, m, km scale), area/distance calculation errors, data not displaying, and transformation errors. Identifies causes, provides diagnostic steps, and solutions.
| Name | Required | Description | Default |
|---|---|---|---|
| symptom | Yes | Describe the problem (e.g., "coordinates shifted by 400m", "area calculation results are wrong", "data not displaying"). 2-500 characters. | |
| context | No | Problem context (optional) |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
With no annotations provided, the description carries full burden for behavioral disclosure. It states the tool 'diagnoses', 'identifies causes', and 'provides diagnostic steps and solutions', which suggests it's a read-only advisory tool. However, it doesn't disclose important behavioral traits like whether it performs actual system checks, requires specific permissions, has rate limits, or what format the solutions take (text, links, code snippets).
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 efficiently structured in two sentences: the first states the core purpose with specific examples, the second explains the diagnostic process. Every element earns its place, though it could be slightly more front-loaded by leading with 'Diagnoses CRS-related problems' rather than 'Troubleshoot CRS-related problems.'
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 diagnostic tool with no annotations and no output schema, the description provides adequate purpose and scope but lacks completeness. It doesn't describe what the output will contain (beyond 'diagnostic steps and solutions'), doesn't explain the tool's limitations, and doesn't address how the context object parameters relate to the troubleshooting process. Given the complexity of CRS troubleshooting, more behavioral context would be helpful.
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 100%, so the schema already documents both parameters thoroughly. The description doesn't add any parameter-specific information beyond what's in the schema - it mentions symptoms like 'coordinate shifts' and 'calculation errors' which align with the schema's symptom parameter examples, but provides no additional semantic context about how parameters should be used together or special considerations.
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's purpose with specific verbs ('troubleshoot', 'diagnoses', 'identifies', 'provides') and resources ('CRS-related problems'), listing concrete examples like coordinate shifts and calculation errors. It distinguishes itself from siblings like compare_crs or validate_crs_usage by focusing on diagnostic problem-solving rather than comparison or validation.
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 usage for CRS-related troubleshooting scenarios through examples, but doesn't explicitly state when to use this tool versus alternatives like suggest_transformation or get_best_practices. No clear exclusions or prerequisites are provided, leaving the agent to infer context from the symptom examples.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
validate_crs_usageB
Validate whether a CRS is appropriate for a specific purpose and location. Detects deprecated CRS usage, area/distance calculation distortion issues, inappropriate zone selection for surveying, and provides improvement suggestions.
| Name | Required | Description | Default |
|---|---|---|---|
| crs | Yes | EPSG code to validate (e.g., "EPSG:3857" or "3857") | |
| purpose | Yes | Intended use | |
| location | Yes | Target location specification |
TDQS
Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?
No annotations are provided, so the description carries full burden. It mentions the tool 'detects' issues and 'provides improvement suggestions', which implies a read-only analysis function, but does not disclose behavioral traits like error handling, performance characteristics, rate limits, or authentication needs. For a validation tool with complex location input, this leaves significant gaps in understanding how it behaves.
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 efficiently structured in two sentences: the first states the core function, and the second enumerates detection capabilities. It is front-loaded with the primary purpose and avoids redundancy. However, it could be slightly more concise by integrating the detection list more seamlessly.
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?
Given the tool's complexity (3 parameters with nested objects, no output schema, and no annotations), the description is moderately complete. It covers the what and why of validation but lacks details on output format, error cases, or limitations. Without annotations or output schema, the agent has insufficient information to fully understand the tool's behavior and results.
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 100%, providing detailed documentation for all parameters. The description adds marginal value by contextualizing the parameters ('for a specific purpose and location') and hinting at the validation logic (e.g., distortion issues relate to 'purpose'), but does not explain parameter interactions or provide syntax examples beyond what the schema already specifies.
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 specific action ('validate whether a CRS is appropriate'), the resource ('a CRS'), and the scope ('for a specific purpose and location'). It distinguishes from siblings by focusing on validation rather than comparison, recommendation, or listing, and explicitly lists the types of issues it detects (deprecated usage, distortion, zone selection).
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 usage context through the listed detection capabilities (e.g., 'inappropriate zone selection for surveying'), but does not explicitly state when to use this tool versus alternatives like 'recommend_crs' or 'compare_crs'. No exclusions or prerequisites are mentioned, leaving the agent to infer appropriate scenarios from the purpose parameter's enum values.
Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.
TDQS
Every tool has a clearly distinct purpose with no ambiguity: compare_crs compares two CRS, get_best_practices provides guidelines, get_crs_detail gives detailed info, list_crs_by_region lists region-specific options, recommend_crs suggests optimal choices, search_crs searches by keywords, suggest_transformation finds transformation paths, troubleshoot diagnoses problems, and validate_crs_usage validates appropriateness. The descriptions clearly differentiate each tool's function, making misselection unlikely.
All tool names follow a consistent verb_noun pattern (e.g., compare_crs, get_best_practices, list_crs_by_region) using snake_case throughout. The verbs are descriptive and aligned with the actions (compare, get, list, recommend, search, suggest, troubleshoot, validate), creating a predictable and readable naming convention across the entire set.
With 9 tools, the count is well-scoped for the EPSG/CRS domain, covering key operations like searching, recommending, comparing, validating, troubleshooting, and providing detailed information. Each tool earns its place by addressing specific needs in coordinate reference system management, avoiding both thin coverage and overwhelming complexity.
The tool set provides complete lifecycle coverage for the EPSG/CRS domain: from discovery (search_crs, list_crs_by_region) and detailed information (get_crs_detail) to selection (recommend_crs, validate_crs_usage), comparison (compare_crs), transformation (suggest_transformation), troubleshooting (troubleshoot), and best practices (get_best_practices). There are no obvious gaps, ensuring agents can handle end-to-end workflows without dead ends.
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