fp-go MCP Server Setup

fp-go MCP Server

Overview

The fp-go MCP (Model Context Protocol) server provides programmatic access to fp-go skills, examples, and documentation. It's located in github.com/IBM/fp-go/gen/v2 and can be integrated into any MCP-compatible client such as Claude Desktop.

Prerequisite: the working directory must contain a go.mod that lists github.com/IBM/fp-go/gen/v2 as a tool dependency (added via go get -tool). The server is launched with go tool gen mcp and uses stdio transport, so no global installation is needed.

The fp-go MCP server exposes four tools:

1. list_skills — List all available fp-go skills
2. use_skill — Retrieve the full content of a specific skill
3. search_examples — Search for Go examples using full-text search
4. get_example — Retrieve a specific example by symbol name

Installation

Add the fp-go generator as a tool dependency in your project:

go get -tool github.com/IBM/fp-go/gen/v2

This makes the tool available via go tool gen without requiring global installation.

Configuration

For Claude Code

Run in the project directory (the one whose go.mod has the tool dependency):

claude mcp add fp-go -- go tool gen mcp

For Claude Desktop (Anthropic)

Add to your Claude Desktop configuration file:

macOS: ~/Library/Application Support/Claude/claude_desktop_config.json

Windows: %APPDATA%\Claude\claude_desktop_config.json

{
  "mcpServers": {
    "fp-go": {
      "command": "go",
      "args": ["tool", "gen", "mcp"],
      "env": {}
    }
  }
}

After configuration, restart Claude Desktop to activate the server.

For Other MCP Clients

The server uses stdio transport and follows the MCP specification. Configure your client to:

• Execute: go tool gen mcp
• Use stdio for communication
• Optionally add --verbose flag for debugging

Available Tools

1. list_skills

Description: List all available fp-go skills with their names, descriptions, and paths.

Parameters: None

Returns:

{
  "skills": [
    {
      "name": "fp-go",
      "description": "Core fp-go patterns and best practices",
      "path": "fp-go"
    },
    {
      "name": "fp-go-pipe-flow",
      "description": "Pipe and Flow composition patterns",
      "path": "fp-go-pipe-flow"
    }
  ]
}

Example Usage:

User: List all available fp-go skills
Assistant: [calls list_skills tool]

Use Cases:

• Discover available skills
• Find skills for specific topics
• Get an overview of fp-go documentation

2. use_skill

Description: Retrieve the full content of a specific skill by name.

Parameters:

• name (required): The skill name from list_skills (e.g., "fp-go", "fp-go-pipe-flow")

Returns:

{
  "name": "fp-go",
  "description": "Core fp-go patterns and best practices",
  "content": "# fp-go v2 — Functional Programming for Go\n\n..."
}

Example Usage:

User: Show me the fp-go-pipe-flow skill
Assistant: [calls use_skill with name="fp-go-pipe-flow"]

Use Cases:

• Load detailed documentation for a specific topic
• Get best practices and examples
• Reference API patterns

Note: The content excludes the YAML frontmatter header — only the markdown content is returned.

3. search_examples

Description: Search for Go examples using full-text search across example names, symbols, packages, documentation comments, and code.

Parameters:

• query (required): a SQLite FTS5 MATCH expression, passed verbatim — not free text and not Go syntax (see Query Rules below)
• package_filter (optional): Filter by package, the path relative to the module root (e.g., "option", "either", "samples/mostly-adequate")

Returns:

{
  "examples": [
    {
      "id": "option::ExampleMap",
      "package": "github.com/IBM/fp-go/v2/option",
      "symbol": "Map",
      "name": "ExampleMap",
      "doc_comment": "// ExampleMap demonstrates mapping over an Option",
      "code": "func ExampleMap() {\n\t...\n}",
      "output": "Some(42)\n",
      "imports": "import O \"github.com/IBM/fp-go/v2/option\"",
      "file": "option/option_test.go"
    }
  ],
  "count": 1
}

Query Rules (violating them yields fts5: syntax error or no such column):

1. Bare words only. Identifiers and plain words such as TraverseArray or Curry1 reader.
2. No dots, no package qualifiers. P.And or reader.Curry1 is a syntax error. Drop the qualifier and put the package into package_filter: query="And", package_filter="predicate".
3. No unquoted punctuation. . : , ( ) [ ] - + ^ are FTS5 operators or invalid (foo-bar is read as column bar). Wrap such text in double quotes to make it a phrase: the query "reader.Curry1" (quotes included) matches the adjacent words reader Curry1.
4. Words are ANDed. And predicate negation Not requires all four words in one example and usually finds nothing. Use 1–3 identifiers, or widen with OR: Not OR And.
5. Whole-word, case-insensitive matching. Curry does not match Curry1; use the prefix wildcard Curry*.
6. Operators AND, OR, NOT must be uppercase; NOT is binary (Map NOT Option), it cannot start a query.

Search Syntax (the values below are the raw query strings):

• Simple terms: Map — finds examples mentioning Map
• Phrases: "point free" — exact phrase match (the double quotes are part of the query)
• Boolean: Map AND Option — both terms required (same as Map Option)
• Alternatives: Chain OR FlatMap — either term
• Wildcards: Trav* — matches Traverse, TraverseArray, etc.
• Package filter: query="Map", package_filter="option" — only option package

package_filter must equal the package path relative to the module root exactly (option, array, samples/mostly-adequate); if a filtered search returns nothing, retry without the filter — not every package has examples for every function.

For an exact lookup of a known symbol, get_example is simpler than search_examples.

Example Usage:

User: Find examples of using Map with Option
Assistant: [calls search_examples with query="Map Option", package_filter="option"]

User: Show me examples of TraverseArray
Assistant: [calls search_examples with query="TraverseArray"]

Use Cases:

• Find examples for specific functions
• Discover usage patterns
• Learn from working code
• Find examples in a specific package

Limits: Returns up to 10 results, ranked by relevance.