diff --git a/README.md b/README.md
index 6ba5ac0..051c328 100644
--- a/README.md
+++ b/README.md
@@ -199,7 +199,7 @@ import {
   createDefaultCoderDelegate,
 } from '@tangle-network/agent-runtime/mcp'
 
-const sandboxClient = new Sandbox({ apiKey: process.env.SANDBOX_API_KEY! })
+const sandboxClient = new Sandbox({ apiKey: process.env.TANGLE_API_KEY! })
 const server = createMcpServer({
   coderDelegate: createDefaultCoderDelegate({ sandboxClient }),
   // researcherDelegate: wire your own — see below.
@@ -210,14 +210,14 @@ await server.serve() // reads JSON-RPC from stdin, writes responses to stdout
 Or run the ready-made bin:
 
 ```bash
-SANDBOX_API_KEY=sk_sandbox_... agent-runtime-mcp
+TANGLE_API_KEY=sk_sandbox_... agent-runtime-mcp
 ```
 
 The bin auto-wires the coder delegate and, when
 `@tangle-network/agent-knowledge` is installed as a peer, the researcher
 delegate. Environment knobs:
 
-- `SANDBOX_API_KEY` — required (unless both `MCP_DISABLE_*` are set)
+- `TANGLE_API_KEY` — required (unless both `MCP_DISABLE_*` are set)
 - `SANDBOX_BASE_URL` — sandbox-SDK base URL override
 - `MCP_MAX_CONCURRENT_SANDBOXES` — kernel `maxConcurrency` cap (default 4)
 - `MCP_CODER_FANOUT_HARNESSES` — comma-separated harness ids for `variants > 1`
diff --git a/package.json b/package.json
index ce6ae42..4ccac34 100644
--- a/package.json
+++ b/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@tangle-network/agent-runtime",
-  "version": "0.20.1",
+  "version": "0.20.2",
   "description": "Reusable runtime lifecycle for domain-specific agents.",
   "homepage": "https://github.com/tangle-network/agent-runtime#readme",
   "repository": {
diff --git a/src/mcp/bin.ts b/src/mcp/bin.ts
index c5132ae..9ead4a6 100644
--- a/src/mcp/bin.ts
+++ b/src/mcp/bin.ts
@@ -11,7 +11,7 @@
  * delegate against `multiHarnessResearcherFanout`.
  *
  * Environment variables:
- *   SANDBOX_API_KEY                  required — passed to `new Sandbox({ apiKey })`
+ *   TANGLE_API_KEY                  required — passed to `new Sandbox({ apiKey })`
  *   SANDBOX_BASE_URL                 optional — sandbox-SDK base URL override
  *   MCP_MAX_CONCURRENT_SANDBOXES     default 4 — kernel maxConcurrency cap
  *   MCP_CODER_FANOUT_HARNESSES       comma-separated harness ids to use for variants > 1
@@ -38,10 +38,10 @@ async function main(): Promise<void> {
   const needsSandbox = wantCoder || wantResearcher
   let sandboxClient: LoopSandboxClient | undefined
   if (needsSandbox) {
-    const apiKey = process.env.SANDBOX_API_KEY
+    const apiKey = process.env.TANGLE_API_KEY
     if (!apiKey && !process.env.AGENT_RUNTIME_MCP_ALLOW_NO_KEY) {
       process.stderr.write(
-        'agent-runtime-mcp: SANDBOX_API_KEY is required (set AGENT_RUNTIME_MCP_ALLOW_NO_KEY=1 to run without it for diagnostics, or set MCP_DISABLE_CODER=1 MCP_DISABLE_RESEARCHER=1 to run the queue-only subset)\n',
+        'agent-runtime-mcp: TANGLE_API_KEY is required (set AGENT_RUNTIME_MCP_ALLOW_NO_KEY=1 to run without it for diagnostics, or set MCP_DISABLE_CODER=1 MCP_DISABLE_RESEARCHER=1 to run the queue-only subset)\n',
       )
       process.exit(2)
     }
@@ -85,7 +85,7 @@ async function loadSandboxClient(apiKey: string | undefined): Promise<LoopSandbo
     return {
       async create() {
         throw new Error(
-          'agent-runtime-mcp: SANDBOX_API_KEY is unset; coder/researcher delegations are disabled in diagnostic mode. Set SANDBOX_API_KEY or use MCP_DISABLE_CODER=1 MCP_DISABLE_RESEARCHER=1 to remove the unsupported tools from the tool list.',
+          'agent-runtime-mcp: TANGLE_API_KEY is unset; coder/researcher delegations are disabled in diagnostic mode. Set TANGLE_API_KEY or use MCP_DISABLE_CODER=1 MCP_DISABLE_RESEARCHER=1 to remove the unsupported tools from the tool list.',
         )
       },
     } satisfies LoopSandboxClient