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Set up Developer MCP

Connect an external MCP client to your Method instance to inspect Tool definitions, look up Object schemas, and validate your implementation. This guide covers the hosted Developer MCP connection. The embedded code editor uses its own local connection; see Tool authoring MCP for that workflow.

Prerequisites

You need:

  • Access to a deployed Method instance with Developer MCP enabled
  • The instance’s Developer MCP endpoint
  • A Method account with permission to manage Tools in that instance

Get the exact endpoint from your Method administrator. For instances that expose Developer MCP at /developer/mcp, use:

https://<instance-host>/developer/mcp

Configure Codex

Codex configures MCP servers in ~/.codex/config.toml. Add a developer entry for your instance:

[mcp_servers.developer]
url = "https://<instance-host>/developer/mcp"
enabled = true

Restart Codex after editing ~/.codex/config.toml, or start a new task so the client reloads MCP config. On first use, Codex should open a browser OAuth flow.

Configure Claude Code

From the repository root, register the hosted server with Claude Code. For a team-shared project config, use project scope:

claude mcp add --transport http --scope project developer https://<instance-host>/developer/mcp

That writes or updates .mcp.json in the repo:

{
  "mcpServers": {
    "developer": {
      "type": "http",
      "url": "https://<instance-host>/developer/mcp"
    }
  }
}

For a private, per-user Claude Code config instead, omit --scope project:

claude mcp add --transport http developer https://<instance-host>/developer/mcp

Run Claude Code from the repo root:

claude

Claude Code may ask you to approve the project-scoped MCP server. Then run /mcp and follow the browser login flow if the server shows as needing authentication. The instance’s OAuth client should allow loopback redirect URLs such as http://localhost:*/* and http://127.0.0.1:*/*, which covers Claude Code and Codex callback path variants.

Configure MCP Inspector

MCP Inspector is useful for verifying that the hosted server is reachable and that Tool schemas are available before wiring an agent to it:

npx @modelcontextprotocol/inspector https://<instance-host>/developer/mcp

If Inspector asks for transport type, choose streamable HTTP.

Verify Tools

After authentication, confirm the MCP client can list tools from the developer server. In Claude Code, use /mcp; in MCP Inspector, connect to the hosted URL and open the tools list.

Expected Developer MCP tool areas include:

  • Tool draft creation and updates
  • Tool validation
  • Tool version creation
  • Compiler and Processor validation
  • Ontology Object Type and tag lookup
  • Tool-development guidance resources and prompts

Troubleshooting

If the client cannot connect, confirm the full endpoint with your Method administrator and check that hosted Developer MCP is enabled.

If Codex does not show the server, confirm the entry is in ~/.codex/config.toml under [mcp_servers.developer], not in .mcp.json.

If Claude Code does not show the server, run claude mcp list from the repo root. Project-scoped .mcp.json servers may stay pending until you trust the workspace and approve them in an interactive claude session.

If the OAuth browser flow fails, check that you are using the right instance and that the instance’s OAuth client allows loopback redirects for native MCP clients.

Next steps

Use the connected server’s development guidance and validation tools to build your capability. See the Tool authoring reference for definition fields, Compiler interfaces, and Processor examples. Available tools depend on your Method instance.