diff --git a/README.md b/README.md
index 7329cdf..6b71fe7 100644
--- a/README.md
+++ b/README.md
@@ -67,6 +67,8 @@ Package installation is separate from the other setup steps in this repo:
 
 Canonical product and architecture memory now lives under `docs/`.
 Start with `docs/README.md` for the documentation map and authoritative entrypoints.
+Agents using the packaged OpenCode `orfe` tool should start with `docs/orfe/opencode-tool-usage.md`.
+The package-root `llms.txt` is a lightweight discovery pointer to that canonical tool-usage doc.
 For operational workflow structure, also see `docs/project/handoffs.md`.
 
 ## Requirements
@@ -191,6 +193,8 @@ Runtime dependency logging is internal to `orfe`:
 
 ## OpenCode plugin
 
+For packaged agent-facing tool guidance, use `docs/orfe/opencode-tool-usage.md`.
+
 Configure OpenCode to load the packaged plugin directly:
 
 ```json
diff --git a/docs/README.md b/docs/README.md
index 26481a5..6730649 100644
--- a/docs/README.md
+++ b/docs/README.md
@@ -41,6 +41,9 @@ Use it to understand what the project is for, which constraints must hold, which
 
 ## Detailed reference material
 
+- `docs/orfe/opencode-tool-usage.md`
+  - canonical agent-facing guide for the packaged OpenCode `orfe` tool
+  - focused on JSON tool requests, structured responses, caller resolution from `context.agent`, and agent-relevant failure guidance
 - `docs/orfe/spec.md`
   - detailed v1 runtime, command, and behavior specification
   - includes the canonical body-contract model for issue and PR artifact validation/provenance
@@ -69,6 +72,7 @@ Use it to understand what the project is for, which constraints must hold, which
 - "Why is it designed this way?": read the ADRs
 - "What is intentionally imperfect right now?": read `docs/project/debt.md`
 - "How should agents hand work to each other?": read `docs/project/handoffs.md`
+- "How do I call the packaged OpenCode tool?": read `docs/orfe/opencode-tool-usage.md`
 - Detailed command/runtime behavior: read `docs/orfe/spec.md`
 - Repo-defined issue/PR body contract rules: read `docs/orfe/spec.md` and `docs/architecture/invariants.md`
 
diff --git a/docs/orfe/opencode-tool-usage.md b/docs/orfe/opencode-tool-usage.md
new file mode 100644
index 0000000..254f66f
--- /dev/null
+++ b/docs/orfe/opencode-tool-usage.md
@@ -0,0 +1,229 @@
+# `orfe` OpenCode tool usage
+
+This is the canonical agent-facing usage guide for the packaged OpenCode `orfe` tool.
+
+Scope:
+
+- OpenCode tool/plugin usage only
+- structured JSON requests and responses
+- current supported tool contract
+
+Out of scope:
+
+- CLI usage
+- repository workflow policy
+- setup/release walkthroughs
+
+For the full v1 command and behavior reference, see `docs/orfe/spec.md`.
+
+## Tool identity
+
+- Tool name: `orfe`
+- Requests are JSON objects
+- `command` is required and uses the canonical space-separated command name
+- Command-specific fields use `snake_case`
+- `repo`, `config`, and `auth_config` are plain input fields when a command supports them
+- `body_contract` selects a repository-defined issue or PR body contract when applicable
+
+Example request shape:
+
+```json
+{
+  "command": "issue get",
+  "issue_number": 123,
+  "repo": "throw-if-null/orfe"
+}
+```
+
+## Caller identity in OpenCode
+
+The OpenCode wrapper reads `context.agent` and resolves the caller from OpenCode context:
+
+- if `context.agent` is a non-empty string, that string is used
+- otherwise, if `context.agent.name` is a non-empty string, that name is used
+
+The wrapper then passes a plain `callerName` string into the shared core runtime.
+
+Important:
+
+- agents should not provide CLI-specific caller environment variables
+- agents should not send `caller_name` in tool input
+- the runtime core does not read `context.agent` directly
+
+If caller context is missing for a caller-mapped command, the tool returns `caller_context_missing`.
+
+## Commands that do not require repo config, auth config, or GitHub
+
+These commands are runtime-only and work without caller context, repo-local config, machine-local auth config, or GitHub access:
+
+- `runtime info`
+- `help`
+
+Examples:
+
+```json
+{
+  "command": "runtime info"
+}
+```
+
+```json
+{
+  "command": "help"
+}
+```
+
+```json
+{
+  "command": "help",
+  "command_name": "issue get"
+}
+```
+
+## Commands that do require repo-local and machine-local configuration
+
+All other supported tool commands currently run through the shared core path and require:
+
+- caller identity from OpenCode `context.agent`
+- repo-local config, normally `.orfe/config.json`
+- machine-local auth config, normally `~/.config/orfe/auth.json`
+
+Many of these commands call GitHub directly. Some commands, such as `issue validate` and `pr validate`, do not create GitHub side effects, but they still use the shared configured runtime path and should be treated as config-dependent tool commands.
+
+## Structured responses
+
+The tool returns the shared `orfe` response envelope.
+
+Success shape:
+
+```json
+{
+  "ok": true,
+  "command": "issue get",
+  "repo": "throw-if-null/orfe",
+  "data": {
+    "issue_number": 123,
+    "title": "Add packaged agent-facing OpenCode tool usage docs (`docs/orfe/opencode-tool-usage.md` and `llms.txt`)",
+    "state": "open",
+    "html_url": "https://github.com/throw-if-null/orfe/issues/123"
+  }
+}
+```
+
+Error shape:
+
+```json
+{
+  "ok": false,
+  "command": "issue get",
+  "error": {
+    "code": "invalid_usage",
+    "message": "Command \"issue get\" requires input field \"issue_number\".",
+    "retryable": false
+  }
+}
+```
+
+Notes:
+
+- successful responses always use `ok: true`
+- runtime failures use `ok: false` with a typed error object
+- `repo` is present for repo-scoped commands and omitted for runtime-only commands such as `help` and `runtime info`
+- the wrapper does not redefine field names for the OpenCode path
+
+## Supported command surface
+
+Use `{"command":"help"}` for structured discovery.
+
+Current command families exposed through the tool contract:
+
+- top-level runtime command: `help`
+- `auth`: `auth token`
+- `issue`: `issue get`, `issue create`, `issue update`, `issue validate`, `issue comment`, `issue set-state`
+- `pr`: `pr get`, `pr validate`, `pr get-or-create`, `pr comment`, `pr submit-review`, `pr reply`
+- `project`: `project get-status`, `project set-status`
+- `runtime`: `runtime info`
+
+## Valid JSON request examples
+
+Read runtime metadata:
+
+```json
+{
+  "command": "runtime info"
+}
+```
+
+Discover one command contract:
+
+```json
+{
+  "command": "help",
+  "command_name": "project set-status"
+}
+```
+
+Mint a caller-scoped installation token:
+
+```json
+{
+  "command": "auth token",
+  "repo": "throw-if-null/orfe"
+}
+```
+
+Read one issue:
+
+```json
+{
+  "command": "issue get",
+  "issue_number": 123
+}
+```
+
+Validate a PR body against the repository contract:
+
+```json
+{
+  "command": "pr validate",
+  "body": "Ref: #123\n\n## Summary\n- Add packaged OpenCode tool usage docs\n\n## Verification\n- Documented current tool contract\n\n## Docs / ADR / debt\n- Added docs; no ADR\n\n## Risks / follow-ups\n- Keep examples aligned with the runtime surface",
+  "body_contract": "implementation-ready@1.0.0"
+}
+```
+
+Set a project status value:
+
+```json
+{
+  "command": "project set-status",
+  "item_type": "issue",
+  "item_number": 123,
+  "status": "In Progress"
+}
+```
+
+## Common agent-relevant failures
+
+- `invalid_usage`
+  - unknown command name
+  - unsupported input field
+  - missing required field
+  - wrong input type
+  - attempted `caller_name` input
+- `caller_context_missing`
+  - OpenCode did not supply usable `context.agent` for a caller-mapped command
+- `caller_name_unmapped`, `config_invalid`, `auth_failed`
+  - local repo/auth setup is incomplete or does not map the resolved caller to a configured bot
+- `github_not_found`
+  - the target issue, PR, or other GitHub resource does not exist in the resolved repo
+- `project_item_not_found`
+  - the target issue or PR is not present on the configured GitHub Project
+
+If you are unsure which command or fields to use, start with `{"command":"help"}` or targeted help for the exact canonical command name.
+
+## Deeper reference
+
+- `docs/orfe/spec.md` is the detailed v1 behavior reference
+- `help` returns structured command discovery and command-level examples through the same tool contract
+
+Keep this file focused on OpenCode tool usage. Treat `docs/orfe/spec.md` as the deeper source for detailed semantics and edge cases.
diff --git a/llms.txt b/llms.txt
new file mode 100644
index 0000000..7e29f8a
--- /dev/null
+++ b/llms.txt
@@ -0,0 +1,7 @@
+# orfe
+
+Canonical agent-facing OpenCode tool usage guide: `docs/orfe/opencode-tool-usage.md`
+
+Detailed runtime/spec reference: `docs/orfe/spec.md`
+
+This file is discovery-only. Do not treat it as a second usage spec.
diff --git a/package.json b/package.json
index b7bd42a..22f2c02 100644
--- a/package.json
+++ b/package.json
@@ -15,7 +15,9 @@
   },
   "files": [
     "dist",
-    "README.md"
+    "README.md",
+    "llms.txt",
+    "docs/orfe/opencode-tool-usage.md"
   ],
   "publishConfig": {
     "registry": "https://registry.npmjs.org",
diff --git a/test/package.test.ts b/test/package.test.ts
index 1d5b1bb..b26f370 100644
--- a/test/package.test.ts
+++ b/test/package.test.ts
@@ -34,6 +34,8 @@ test('package metadata exposes installable orfe CLI wiring', async () => {
   assert.equal(scripts?.prepack, 'npm run build');
   assert.ok(files?.includes('dist'));
   assert.ok(files?.includes('README.md'));
+  assert.ok(files?.includes('llms.txt'));
+  assert.ok(files?.includes('docs/orfe/opencode-tool-usage.md'));
   assert.ok(!files?.includes('docs'));
   assert.equal(exportsField?.['./server'], './dist/plugin.js');
   assert.equal(publishConfig?.registry, 'https://registry.npmjs.org');