MCP Tools & Resources

RepoRelay implements the Model Context Protocol (MCP) to provide code context directly to LLM agents. The MCP server exposes 7 tools, 2 resources, and 3 prompts.

Server

The MCP server runs as an HTTP service (pnpm dev:mcp), serving the MCP protocol at /mcp and a health check at /health on MCP_SERVER_PORT (default 3000). Clients connect through the MCP proxy, which handles language auto-detection and forwards requests.

Client Configuration

All clients connect via the MCP proxy (npx reporelay --server <url>).

Claude Desktop / Cursor

{
  "mcpServers": {
    "reporelay": {
      "command": "npx",
      "args": ["reporelay", "--server", "http://localhost:3000/mcp"]
    }
  }
}

OpenCode

{
  "mcp": {
    "reporelay": {
      "type": "local",
      "command": ["npx", "reporelay", "--server", "http://localhost:3000/mcp"]
    }
  }
}

See MCP Integration > Connecting Clients for remote server examples.

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Tools

search_code

Hybrid lexical + vector search across indexed repositories. Combines BM25 full-text search with vector similarity via Reciprocal Rank Fusion (RRF).

Parameter	Type	Required	Description
query	string	yes	Search query (min 1 character)
repo	string	no	Filter by repository name
ref	string	no	Filter by ref/tag (supports semver constraints)
limit	number	no	Max results, 1-100 (default 20)
languages	string[]	no	Language filter override (e.g. ["typescript", "javascript"])

Example:

search_code({ query: "authentication middleware", repo: "my-api", limit: 10 })
search_code({ query: "auth", languages: ["typescript", "python"] })

---

get_file

Retrieve file content by repository and path. Tries raw file from the git mirror first, falls back to indexed chunks. Optionally includes a symbol list with signatures.

Parameter	Type	Required	Description
repo	string	yes	Repository name
path	string	yes	File path within the repo
ref	string	no	Ref/tag (supports semver constraints)
includeSymbols	boolean	no	Include symbol list with signatures

Example:

get_file({ repo: "my-api", path: "src/auth/login.ts", includeSymbols: true })

---

get_symbol

Fetch a specific symbol (function, class, interface, etc.) by name. Returns the symbol's source code, location, and optionally which files import it.

Parameter	Type	Required	Description
repo	string	yes	Repository name
symbolName	string	yes	Symbol name to look up
ref	string	no	Ref/tag (supports semver constraints)
includeImports	boolean	no	Show files that import this symbol
languages	string[]	no	Language filter override (e.g. ["typescript", "javascript"])

Example:

get_symbol({ repo: "my-api", symbolName: "buildApp", includeImports: true })

---

find

Search for files or symbols by a glob-style name pattern.

Parameter	Type	Required	Description
pattern	string	yes	Search pattern (glob-style wildcards)
kind	string	yes	"file" or "symbol"
repo	string	yes	Repository name
ref	string	no	Ref/tag (supports semver constraints)
languages	string[]	no	Language filter override (e.g. ["typescript", "javascript"])

Example:

find({ pattern: "**/auth/*.ts", kind: "file", repo: "my-api" })
find({ pattern: "create*", kind: "symbol", repo: "my-api" })

---

find_references

Find files that import a given symbol name. Useful for understanding how a function or class is used across the codebase.

Parameter	Type	Required	Description
repo	string	yes	Repository name
symbolName	string	yes	Symbol name to search for
ref	string	no	Ref/tag (supports semver constraints)

Example:

find_references({ repo: "my-api", symbolName: "login" })

---

build_context_pack

Build task-specific context packs from indexed code. Four strategies are available:

Strategy	Description
explain	Understand how a library or module works
implement	Get guidance for building with existing patterns
debug	Debug an error with relevant code context
recent-changes	Review recent changes between two refs (requires fromRef)

Parameter	Type	Required	Description
repo	string	yes	Repository name
task	string	yes	Strategy: explain, implement, debug, recent-changes
ref	string	no	Ref/tag (supports semver constraints)
fromRef	string	no	Base ref for recent-changes strategy
query	string	no	Guiding query for context gathering
paths	string[]	no	Specific file paths to focus on
maxTokens	number	no	Token budget (default 8192)

Example:

build_context_pack({
  repo: "my-api",
  task: "implement",
  query: "Add rate limiting to the auth endpoints",
  maxTokens: 4096
})

---

list_repos

List all registered repositories with their indexing status and indexed refs.

Parameter	Type	Required	Description
languages	string[]	no	Language filter override (e.g. ["typescript", "javascript"])

Example:

list_repos({})
list_repos({ languages: ["go", "rust"] })

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Resources

MCP resources allow clients to browse and read indexed content via URI templates.

File Content

Property	Value
URI Template	reporelay://{repo}/{ref}/{path+}
MIME Type	text/plain
Description	Retrieve indexed file content

Example URI: reporelay://my-api/v1.0.0/src/auth/login.ts

Directory Tree

Property	Value
URI Template	reporelay://{repo}/{ref}/tree
MIME Type	text/plain
Description	List all file paths in a ref

Example URI: reporelay://my-api/v1.0.0/tree

Resource listings enumerate all repositories with ready refs, so clients can browse available content without calling tools first.

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Prompts

Prompts provide pre-built templates for common workflows. Each prompt calls build_context_pack internally and returns a formatted message with relevant code context.

explain-library

Understand how a library or module works.

Argument	Type	Required	Description
repo	string	yes	Repository name
query	string	no	Module or topic to focus on
ref	string	no	Ref/tag (semver constraints)

Generated message: "Explain the architecture and key concepts of {query or repo}. Use the following indexed code context: ..."

implement-feature

Get guidance for building with existing patterns.

Argument	Type	Required	Description
repo	string	yes	Repository name
query	string	yes	Feature description
ref	string	no	Ref/tag (semver constraints)

Generated message: "I want to implement: {query}. Follow the existing patterns in the codebase. Here is the relevant context: ..."

debug-issue

Debug an error with relevant code context.

Argument	Type	Required	Description
repo	string	yes	Repository name
query	string	yes	Issue description
ref	string	no	Ref/tag (semver constraints)

Generated message: "I'm debugging this issue: {query}. Here is the relevant code context: ..."

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Semver Support

All tools and resources that accept a ref parameter support semver constraint resolution. Instead of specifying an exact tag, you can use semver ranges:

ref: "^1.0.0"    → resolves to latest matching tag (e.g. v1.5.2)
ref: "~2.1.0"    → resolves to latest patch (e.g. v2.1.7)
ref: ">=3.0.0"   → resolves to latest matching tag

This is useful when agents need "the latest v1.x" without knowing the exact version.

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Language Filtering

Four tools (search_code, get_symbol, find, list_repos) accept an optional languages parameter. This allows per-request language filtering — only repos whose indexed refs contain the specified languages above the configured threshold are included in results.

Valid language values: typescript, javascript, python, go, java, kotlin, rust, c, cpp, markdown.

When using the MCP proxy, detected languages from the developer's working directory are automatically injected into these tools. Explicitly provided languages values always take priority over auto-detected ones.