Entity Bind and Claude Code

1. 01

   Prove the endpoint answers

   Run both of these before you touch a config file, because the two commonest failures present identically as a broken client. A 421 means the deployment's public base URL does not name the hostname your client puts in the Host header; that check runs before authentication, before routing and before any tool body, so no amount of editing the client will move it. The health probes sit outside the check, which is why a green /healthz does not on its own show that tool calls are being admitted. The tools/list call shows that.

   Prove the endpoint answers

   curl -s https://host.example.com/healthz
   
   curl -s https://host.example.com/mcp \
     -H "Authorization: Bearer $ENTITYBIND_API_KEY" \
     -H "Content-Type: application/json" \
     -H "Accept: application/json, text/event-stream" \
     -d '{"jsonrpc":"2.0","id":1,"method":"tools/list"}'

2. 02

   Add the server

   Project scope puts this in a JSON file at the root of the repository; user scope puts the same object in your own Claude Code configuration. The key under mcpServers is the name the client displays and nothing on either side of the wire reads it. The path is /mcp, the header is Authorization and the scheme is Bearer on every remote shape.

   Add the server

   {
     "mcpServers": {
       "entitybind": {
         "type": "http",
         "url": "https://host.example.com/mcp",
         "headers": {
           "Authorization": "Bearer rk_YOUR_KEY_HERE"
         }
       }
     }
   }

3. 03

   Keep the key out of the repository

   A project-scoped config file is a file somebody commits. The rk_ key you create in your Entity Bind workspace is the whole credential — there is nothing further to mint, register or exchange, and no separate MCP credential exists — so a committed config is a committed credential. Use the user-scoped file, or your client's own environment expansion where it has one. If a key does reach a repository, revoke it in your workspace and create a new one.

4. 04

   Tell the agent what an abstention is

   Put two things in the agent's own instructions before it calls anything. An abstention is a successful answer rather than an error: the tool returns a ranked shortlist, a typed reason, the column that would have decided, and a review id, and it costs nothing. And a confidence number is read against the recorded evidence behind that particular decision, not as a universal score. Confidence bounds depend on the recorded evidence population; there is no universal score for every match. Read match_confidence_basis and the evidence. A 0.99 filter can return some v8 adjudicated matches while excluding valid identifier matches, so validate its coverage cost on your own inputs.

Claude Code sits with Claude Desktop and Cursor on the same shelf: configure and call. If you are weighing a shipped integration against a pattern, the line between the two shelves is drawn on the hub.