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@ -1,10 +1,37 @@
# MCP Servers
Pi connects to [Model Context Protocol](https://modelcontextprotocol.io) servers over stdio or streamable HTTP and makes their tools available to the model.
Pi connects to [Model Context Protocol](https://modelcontextprotocol.io) servers over stdio or streamable HTTP and makes their tools and resources available to the model.
## Quick setup
Add a local stdio server, check the connection, then start Pi:
```bash
pi mcp add filesystem -- npx -y @modelcontextprotocol/server-filesystem .
pi mcp list
pi
```
For a remote server:
```bash
pi mcp add docs --url https://example.com/mcp --bearer-token-env-var DOCS_TOKEN
pi mcp list
```
These commands add user-level servers by default. Add `--local` or `-l` to write the project configuration instead:
```bash
pi mcp add -l tools --env API_KEY='${TOOLS_KEY}' -- uvx tools-mcp
```
Use `/mcp` inside an interactive session to inspect connections, sign in, reconnect, change exposure, or enable and disable servers. Run `/reload` after adding, removing, or changing a server outside the session.
## Configure servers
Add servers to `~/.pi/agent/mcp.json`, or to `.pi/mcp.json` in a project. The format matches other MCP clients, so existing `mcpServers` entries can be copied over:
Pi reads user-level servers from `~/.pi/agent/mcp.json` and project servers from `.pi/mcp.json`. Project configuration is read only after [project trust](security.md#understand-project-trust) is granted. A project entry replaces a user-level entry with the same name.
The format matches other MCP clients:
```json
{
@ -22,71 +49,59 @@ Add servers to `~/.pi/agent/mcp.json`, or to `.pi/mcp.json` in a project. The fo
}
```
- stdio servers take `command`, `args`, `env`, and `cwd`. Relative `cwd` resolves against the session directory. A leading `~/` in `command`, an argument, or `cwd` names the home directory.
- HTTP servers take `url`, `headers`, and `oauth` (see [Sign in with OAuth](#sign-in-with-oauth)). The legacy SSE transport is not supported.
- `env` and `headers` values can reference environment variables (`${NAME}`) or commands (`!command`), like provider API keys.
- `timeout` sets the per-request timeout in seconds (default 60). Progress notifications from the server reset it.
- `enabled: false` keeps an entry without connecting to it.
Stdio servers use `command`, `args`, `env`, and `cwd`. Relative `cwd` values resolve against the session directory. A leading `~/` in `command`, an argument, or `cwd` names the home directory.
Project entries replace global entries with the same name. A project `mcp.json` is only read after the project is trusted, because stdio servers run commands.
HTTP servers use `url`, `headers`, and `oauth` (see [Authenticate with OAuth](#authenticate-with-oauth)). The legacy SSE transport is not supported.
`pi mcp add` and `pi mcp remove` edit the file from a shell (see [MCP commands](cli.md#mcp-commands)):
Both server types support:
```bash
pi mcp add filesystem -- npx -y @modelcontextprotocol/server-filesystem .
pi mcp add docs --url https://example.com/mcp --bearer-token-env-var DOCS_TOKEN --exposure direct
pi mcp add -l tools --env API_KEY='${TOOLS_KEY}' -- uvx tools-mcp
pi mcp remove docs
```
- `timeout`: per-request timeout in seconds (default 60). Progress notifications reset it.
- `enabled: false`: keep the entry without connecting to it.
- `exposure` and `toolExposure`: control how tools reach the model (see [Control tool exposure](#control-tool-exposure)).
Rules that are easy to get wrong:
Keep personal servers and servers with credentials in the user-level file. Use the project file only for servers the project requires, and only in trusted projects.
- Server names may only contain letters, digits, `_`, and `-`. Tools are named `mcp__<server>__<tool>`.
- `type` is optional: a `command` makes a stdio server and a `url` a streamable HTTP server. When present, it must be `stdio`, `http`, or `streamable-http`. `sse` is rejected; most servers that document an SSE endpoint also serve streamable HTTP, often at `/mcp` instead of `/sse`.
- `command` is a single executable and `args` its arguments, not one shell string.
- Keep secrets out of the file: use `${NAME}` for environment variables, as in `"Authorization": "Bearer ${GITHUB_TOKEN}"`, or `!command` to run a command. A command must make up the whole value, so it has to print the header value itself: `"Authorization": "!echo Bearer $(gh auth token)"`.
- Invalid entries are skipped and reported; the other servers still connect.
### Configuration rules
## Set up servers
- Server names may contain only letters, digits, `_`, and `-`. Tools are named `mcp__<server>__<tool>`.
- `type` is optional. A `command` selects stdio and a `url` selects streamable HTTP. When present, `type` must be `stdio`, `http`, or `streamable-http`.
- `sse` is rejected. Servers that document an SSE endpoint often also provide streamable HTTP, commonly at `/mcp` instead of `/sse`.
- `command` is one executable and `args` contains its arguments. It is not a shell command string.
- `env` and `headers` values can use environment variables such as `${GITHUB_TOKEN}`. They can also run a command with `!command`, but the command must make up the whole value, for example `"Authorization": "!echo Bearer $(gh auth token)"`.
- Invalid entries are reported and skipped without preventing other servers from connecting.
When asked to add an MCP server, the agent should:
`pi mcp add` and `pi mcp remove` cover common changes from a shell. See [MCP commands](cli.md#mcp-commands) for their options.
1. Add simple servers with `pi mcp add` (add `-l` for the project file), or edit `mcp.json` directly for settings the command does not cover. Put personal servers and servers with credentials in `~/.pi/agent/mcp.json`. Use the project `.pi/mcp.json` only for servers the project itself needs, and only in trusted projects.
2. Convert entries written for other clients:
- Claude Desktop, Claude Code, and Cursor use the same `mcpServers` shape; copy the entry.
- VS Code uses a top-level `servers` object and `inputs` prompts; move the entry under `mcpServers` and replace `${input:...}` with `${NAME}` environment variables.
- Codex uses TOML (`[mcp_servers.<name>]` with `command`, `args`, `env`, or `url`); write the same fields as JSON.
- opencode uses `"type": "local"` with `command` as an array (split it into `command` and `args`), `"type": "remote"` for URLs, `environment` for `env`, and `{env:NAME}` for `${NAME}`.
3. Run `pi mcp list` to check the entry. It connects to every enabled server and prints the state, the tools, and errors such as the stderr of a stdio server that failed to start. It exits with 1 while anything is wrong.
4. For a server that needs a sign-in, run `pi mcp login <server>`. It opens the authorization page in the user's browser and waits until the user approves access; tell the user to approve it. A running session uses the new credentials on its next turn.
5. Tell the user to run `/reload` (or start a new session) so the running session connects to added or changed servers.
### Inspect or change a server
Pi connects when a session starts. The first prompt waits up to 10 seconds for startup connections; the tools of servers that take longer become available once they connect. HTTP connections that fail with a network error or a transient status (408, 429, 5xx) are retried twice. A server that drops its connection shows as disconnected and is reconnected on the next call. When a server announces that its tool list changed, new tools are added and withdrawn tools become unreachable until the server offers them again.
`/mcp` lists configured servers with their state, tool count, exposure, and configuration source. Servers that need attention appear first. Select a server to inspect its tools and connection details, reconnect, sign in or out, change exposure, or enable and disable it.
Config errors, servers that failed to connect, and servers that need a sign-in are reported once after startup.
Exposure and enabled-state changes are saved to the file that defines the server without replacing unrelated content. Disabled servers remain listed. Outside the interactive TUI, `/mcp` prints server status; `/mcp login <server>`, `/mcp logout <server>`, and `/mcp reconnect <server>` perform those actions directly.
Log messages servers send with MCP logging notifications are appended to `~/.pi/agent/mcp.log` as `<time> [<server>] <level> <logger>: <message>`. The file is moved to `mcp.log.1` when it grows past 5 MB.
Shell commands work without a session: `pi mcp add`, `pi mcp remove`, `pi mcp list`, `pi mcp login`, and `pi mcp logout`. Shell commands do not load extensions.
## Manage servers
### Diagnose connection problems
`/mcp` opens the server manager. It lists every configured server with its state, tool count, exposure, and whether it comes from the global or the project `mcp.json`; servers that need attention come first. Select a server to:
Run `pi mcp list` to connect to every enabled server and print its state, tools, and errors. It exits with status 1 when an entry is invalid or an enabled server is not connected. `/mcp` shows the full connection error and the tail of stderr from a failed stdio server.
- sign in, for OAuth servers that need it (see [Sign in with OAuth](#sign-in-with-oauth))
- see its tools, its command or URL, and the full connection error, including the tail of a stdio server's stderr
- reconnect
- sign out, which deletes the stored OAuth credentials
- change its exposure (see [Exposure](#exposure))
- disable or enable it
Pi reports configuration errors, failed connections, and required sign-ins once after startup. Server logging notifications are appended to `~/.pi/agent/mcp.log` as `<time> [<server>] <level> <logger>: <message>`. The file moves to `mcp.log.1` after it grows past 5 MB.
Exposure changes and enabling or disabling are saved to the `mcp.json` that defines the server; other content of the file is kept. Disabled servers stay listed so they can be enabled again.
Pi connects when a session starts. The first prompt waits up to 10 seconds for startup connections; tools from slower servers become available when they connect. HTTP network errors and transient statuses (408, 429, and 5xx) are retried twice. A dropped connection is shown as disconnected and reconnects on the next call. When a server announces a changed tool list, new tools are added and withdrawn tools become unreachable.
Outside the interactive TUI, `/mcp` prints the server status. `/mcp login <server>`, `/mcp logout <server>`, and `/mcp reconnect <server>` run those actions directly.
Stopping a stdio server closes its stdin, sends SIGTERM, then sends SIGKILL to its process group. This also stops servers launched through wrappers such as `npx` or `uvx`.
From a shell, `pi mcp add`, `pi mcp remove`, `pi mcp list`, `pi mcp login <server>`, and `pi mcp logout <server>` manage servers without a session (see [MCP commands](cli.md#mcp-commands)).
## Migrate configuration from another client
Stopping a stdio server closes its stdin, then sends SIGTERM and finally SIGKILL to its whole process group, so servers started through wrappers such as `npx` or `uvx` do not linger.
Move the converted entry under `mcpServers` in `mcp.json`, then run `pi mcp list` to validate it.
## Sign in with OAuth
| Client | Conversion |
|---|---|
| Claude Desktop, Claude Code, or Cursor | Copy the existing `mcpServers` entry. |
| VS Code | Move an entry from the top-level `servers` object and replace `${input:...}` prompts with `${NAME}` environment variables. |
| Codex | Convert `[mcp_servers.<name>]` TOML fields such as `command`, `args`, `env`, and `url` to JSON. |
| OpenCode | Convert `"type": "local"` to a stdio entry, split its `command` array into `command` and `args`, rename `environment` to `env`, and replace `{env:NAME}` with `${NAME}`. Convert `"type": "remote"` to a URL entry. |
## Authenticate with OAuth
Remote servers that use OAuth, such as Sentry, need no credentials in `mcp.json`:
@ -98,11 +113,11 @@ Remote servers that use OAuth, such as Sentry, need no credentials in `mcp.json`
}
```
When such a server rejects the connection, `/mcp` shows it as needing sign-in. Select it and choose "Sign in" (or run `/mcp login sentry`, or `pi mcp login sentry` in a shell) to open the authorization page in your browser. After you approve access, the browser redirects to a temporary server on `127.0.0.1` and pi connects. If the browser runs on another machine, for example over SSH, paste the URL it was redirected to into the sign-in screen instead.
When the server rejects an unauthenticated connection, `/mcp` shows that it needs sign-in. Select "Sign in", run `/mcp login sentry`, or run `pi mcp login sentry`. Pi opens the authorization page and waits for approval. If the browser runs on another machine, such as over SSH, paste its redirected URL into the sign-in screen. A running session uses the new credentials on its next turn.
Pi registers itself with the authorization server (dynamic client registration), stores tokens in `~/.pi/agent/mcp-auth.json`, and refreshes access tokens automatically when they expire or the server rejects them. If the server later asks for more scope than was granted, it shows as needing sign-in again, and signing in requests the new scope. "Sign out" in `/mcp` (or `/mcp logout sentry`) deletes the stored credentials.
Pi registers itself with the authorization server, stores tokens in `~/.pi/agent/mcp-auth.json`, and refreshes access tokens when they expire or the server rejects them. If a server later requests additional scope, Pi asks for sign-in again. Signing out deletes the stored credentials.
OAuth applies to HTTP servers without an `Authorization` header. For authorization servers that do not support dynamic client registration, configure a pre-registered client:
OAuth applies to HTTP servers without an `Authorization` header. For a server that does not support dynamic client registration, configure a registered client:
```json
{
@ -115,21 +130,25 @@ OAuth applies to HTTP servers without an `Authorization` header. For authorizati
}
```
The redirect URI must match the one registered for the client. `callbackPort` fixes it to `http://127.0.0.1:<port>/callback`. For another redirect URI, set `callbackUrl`, for example `"callbackUrl": "http://localhost:8080/oauth/callback"`. It must be an `http` URI on `localhost`, `127.0.0.1`, or `[::1]`, and is sent exactly as written. Without a port in `callbackUrl`, pi listens on `callbackPort`, or on a free port, and adds it to the URI; authorization servers accept any port for loopback redirects (RFC 8252). `clientSecret` is optional and can reference environment variables or commands.
The redirect URI must match the registered URI. `callbackPort` uses `http://127.0.0.1:<port>/callback`. To use another URI, set `callbackUrl`; it must use HTTP on `localhost`, `127.0.0.1`, or `[::1]`. Pi sends it exactly as written. When `callbackUrl` omits a port, Pi uses `callbackPort` or a free port and adds it to the URI, as allowed for loopback redirects by RFC 8252. `clientSecret` is optional and can use an environment variable or command.
`scope` sets the scopes to request, separated by spaces, for servers that do not advertise the ones they need. Without it, pi requests the scopes the server advertises. When a server later asks for more scope, pi requests those on top of `scope`.
Set `scope` to a space-separated list for servers that do not advertise their required scopes. Otherwise, Pi requests the advertised scopes. Later scope requests are added to the configured value.
## Exposure
## Control tool exposure
Each server's tools are registered as `mcp__<server>__<tool>`. The `exposure` setting controls how the model reaches them:
Each server tool is registered as `mcp__<server>__<tool>`. The server's `exposure` determines how the model reaches it:
- `codemode` (default): the tools are callable from [`codemode`](cli.md#tools) scripts and listed in the `codemode` tool's description, but are not declared to the model. Large MCP tool lists stay out of the model's tool declarations, and scripts can call several MCP tools, in parallel if needed, while returning only the part of the result the model needs. Pi activates the `codemode` tool when such a server connects. Large servers do not fill the description: declarations share a token budget, and scripts find the remaining tools with `searchTools()` (see [`codemode`](cli.md#tools)).
- `codemode-deferred`: like `codemode`, but the tools are not listed in the `codemode` tool's description either; it only names the server and its tool count. Scripts call them by name and find them with `searchTools()` or in `ALL_TOOLS`. Use it for large servers that codemode scripts use rarely.
- `deferred`: the tools are not declared to the model until the [`tool_search`](cli.md#tools) tool loads them. The model searches, and the matches are declared from its next call on and called directly, without codemode. Pi activates the `tool_search` tool when such a server connects. Use it for large servers without codemode.
- `direct`: the tools are declared to the model like built-in tools, and are also callable from codemode.
- `hidden`: the tools are registered but cannot be called.
| Exposure | Behavior | Typical use |
|---|---|---|
| `codemode` (default) | Callable from [`codemode`](cli.md#tools) scripts and listed in its description, but not declared directly to the model. | General MCP servers, especially when scripts should combine or filter calls. |
| `codemode-deferred` | Callable from codemode, but omitted from its inline tool declarations. Scripts find tools with `searchTools()`, `describeTool()`, or `ALL_TOOLS`. | Large, infrequently used servers. |
| `deferred` | Not declared until [`tool_search`](cli.md#tools) loads a match for the next model call. | Large servers whose tools should be called directly after discovery. |
| `direct` | Declared to the model like a built-in tool and also callable from codemode. | Small, frequently used tool sets. |
| `hidden` | Registered but unreachable. | Servers or tools that should remain unavailable. |
`toolExposure` sets the exposure of single tools and overrides `exposure` for them. Keys are tool names as the server offers them, or patterns where `*` matches any characters. An exact name wins over patterns; among patterns, the first match in the object wins. With `hidden` as the server's exposure, only the listed tools are reachable:
Pi activates `codemode` when a server with `codemode` or `codemode-deferred` exposure connects. It activates `tool_search` for a server with `deferred` exposure. Codemode declarations share the token budget configured by `codemode.inlineBudget`; scripts can find omitted tools with `searchTools()` or `describeTool()`.
`toolExposure` overrides the server exposure for individual tools. Keys are exact server tool names or patterns where `*` matches any characters. Exact names win over patterns; among patterns, the first match wins. A server with `hidden` exposure can expose only selected tools:
```json
{
@ -147,42 +166,50 @@ Each server's tools are registered as `mcp__<server>__<tool>`. The `exposure` se
}
```
`pi mcp list` marks tools whose exposure differs from the server's, and the Tools view in `/mcp` shows it too.
`pi mcp list` marks tools whose exposure differs from their server. The Tools view in `/mcp` also shows the effective exposure.
Tools that are not declared (`codemode`, `codemode-deferred`, and `deferred` exposure) are reachable through either tool: codemode scripts can call all of them, and `tool_search` can load any of them. For example, with `codemode` active, scripts can call the tools of a `deferred` server, and with `tool_search` active, the model can load the tools of a `codemode` server.
Tools with `codemode`, `codemode-deferred`, or `deferred` exposure can be reached through either indirect mechanism: codemode scripts can call them, and `tool_search` can load them. Codemode calls do not depend on the active tool set, so they remain available after `/tree`, resume, and fork. Tools loaded by `tool_search` are recorded in the transcript and remain declared on that branch.
Tools called from codemode scripts do not depend on the active tool set, so they stay callable after `/tree`, resume, and fork. Tools loaded by `tool_search` are recorded in the transcript like any other tool change and stay declared on that branch. To keep pi from activating the `codemode` tool, set `"autoEnableCodemode": false` at the top level of `mcp.json`, next to `mcpServers`. A project `mcp.json` value overrides the global one. Pi warns once when neither `codemode` nor `tool_search` is active, since the tools then cannot be called.
To prevent automatic codemode activation, set `"autoEnableCodemode": false` beside `mcpServers`. A project value overrides the user-level value. Pi warns once when neither `codemode` nor `tool_search` is active and non-direct tools cannot be called.
Text results over 20KB reach the model with the middle cut out, in the format Codex uses: the start and end of the text around a `…N chars truncated…` marker. The full text is saved to a temp file whose path the result names. Codemode scripts always receive the whole result, so a script can filter a large result down to what the model needs.
Text results over 20 KB reach the model with their middle removed around a `…N chars truncated…` marker. The full text is saved to a temporary file named in the result. Codemode scripts receive the complete result and can reduce it before returning output to the model.
Codemode scripts receive an MCP tool's whole `CallToolResult` (`content` blocks as sent by the server, `structuredContent`, and `isError`), and the `codemode` description declares it as `CallToolResult<T>`. A result with `isError` resolves in scripts and is reported to the model as an error for direct calls. `image(result.content[0])` forwards an image block to the model. The server's `instructions` describe its tools in the `codemode` description.
Codemode scripts receive the complete MCP `CallToolResult`, including `content`, `structuredContent`, and `isError`. A result with `isError` resolves inside scripts but is reported as an error for direct calls. `image(result.content[0])` forwards an image block. Server instructions are included in the codemode description.
## Resources
## Use resources
When a connected server offers [resources](https://modelcontextprotocol.io/specification/2025-11-25/server/resources), pi adds the resource tools Codex and opencode use:
When a connected server offers [resources](https://modelcontextprotocol.io/specification/2025-11-25/server/resources), Pi adds the resource tools used by Codex and OpenCode:
- `list_mcp_resources` lists resources as JSON: `{ server?, resources: [{ server, uri, name, ... }], nextCursor? }`. With `server`, it lists one page of that server, and `cursor` continues with the next one. Without, it lists every resource of every server.
- `list_mcp_resource_templates` lists URI templates for resources the servers do not list, in the same way.
- `read_mcp_resource` reads a resource given `server` and `uri`. Text resources reach the model as text and images as images; other binary resources are saved to temp files, and the model sees the file path. Scripts receive `{ server, uri, contents }`.
- `list_mcp_resources` lists resources as JSON: `{ server?, resources: [{ server, uri, name, ... }], nextCursor? }`. With `server`, it lists one page; `cursor` continues with the next page. Without `server`, it lists every resource from every server.
- `list_mcp_resource_templates` lists URI templates for resources the servers do not list directly.
- `read_mcp_resource` reads a resource by `server` and `uri`. Text reaches the model as text and images as images. Other binary resources are saved to temporary files, and the model receives the path. Scripts receive `{ server, uri, contents }`.
The tools reach every enabled server with resources whose exposure is not `hidden`, and take the widest exposure among them: `direct` if one of the servers is direct, else `codemode`, else `codemode-deferred`, else `deferred`. Resource links in tool results name `read_mcp_resource` and the server.
These tools reach every enabled, non-hidden server with resources. Their exposure is the widest exposure among those servers: `direct`, then `codemode`, `codemode-deferred`, or `deferred`. Resource links in tool results identify `read_mcp_resource` and the server.
Resources for MCP Apps (`ui://` URIs or `text/html;profile=mcp-app`) are left out of the listings, since pi does not render them, and so are resource icons.
Resources for MCP Apps, identified by `ui://` URIs or `text/html;profile=mcp-app`, are omitted because Pi does not render them. Resource icons are also omitted.
Reading and listing resources is retried once after a transient HTTP error (408, 429, 5xx). Tool calls are not retried, since the server may have run them.
Reading and listing resources is retried once after a transient HTTP error (408, 429, or 5xx). Tool calls are not retried because the server may already have performed them.
## Permissions
Every MCP call goes through pi's tool pipeline, so `tool_call` and `tool_result` extension handlers, including permission gates, apply to MCP tools. Calls made from codemode scripts carry the `codemode` call's id as `parentToolCallId`. `pi.getAllTools()` reports the tool annotations servers declare (`readOnlyHint`, `destructiveHint`, `idempotentHint`, `openWorldHint`), so a permission extension can confirm only calls that change something (see [Extensions](extensions.md#tool-exposure)). The resource tools are marked read-only.
Every MCP call passes through Pi's tool pipeline. Extension `tool_call` and `tool_result` handlers, including permission gates, therefore apply to MCP tools. Calls made from codemode scripts carry the codemode call ID as `parentToolCallId`.
## Servers from extensions
`pi.getAllTools()` reports the annotations declared by each server: `readOnlyHint`, `destructiveHint`, `idempotentHint`, and `openWorldHint`. Permission extensions can use these hints to decide which calls require confirmation (see [Tool exposure](extensions.md#tool-exposure)). Resource tools are marked read-only.
Extensions can add servers for the current session with `pi.registerMcpServer(name, config)`, using the same config shape as `mcp.json` (see [Extensions](extensions.md#mcp-servers)). They connect like configured servers and appear in `/mcp` with the extension as their source. Enabling, disabling, and exposure changes for them apply to the current session only. A server in `mcp.json` with the same name takes precedence; `/mcp` lists the overridden registration. `pi mcp` shell commands do not load extensions and only see `mcp.json` servers.
## Extensions and SDK
## Other MCP extensions
### Add servers from extensions
An installed extension that registers the `/mcp` command, such as `pi-mcp-adapter`, replaces the built-in MCP support: pi then neither reads `mcp.json` in sessions nor connects servers, and `/mcp` belongs to that extension. Remove the extension to use the built-in support. Likewise, an extension that registers a tool named `codemode` or `tool_search` replaces the built-in tool of that name. `pi mcp` shell commands always use the built-in support.
Extensions can add servers for the current session with `pi.registerMcpServer(name, config)`, using the same shape as an `mcpServers` entry (see [MCP servers in extensions](extensions.md#mcp-servers)). Registered servers connect like configured servers and appear in `/mcp` with the extension as their source.
## SDK
Changes to enabled state or exposure apply only to the current session. A file-configured server with the same name takes precedence, and `/mcp` lists the overridden registration. `pi mcp` shell commands do not load extensions and only see file-configured servers.
SDK sessions do not load the built-in extensions. Add the MCP extension, the codemode extension for `codemode` and `codemode-deferred` servers, and the tool search extension for `deferred` servers to the resource loader. See [SDK](sdk.md#codemode-mcp).
### Replace the built-in MCP support
An installed extension that registers `/mcp`, such as `pi-mcp-adapter`, replaces the built-in MCP support for sessions. Pi then does not read `mcp.json` or connect its servers in a session, and `/mcp` belongs to the extension. Remove the extension to restore the built-in behavior.
An extension that registers `codemode` or `tool_search` similarly replaces the built-in tool with that name. Shell-level `pi mcp` commands always use the built-in implementation.
### Use MCP from the SDK
SDK sessions do not load built-in extensions. Add the MCP extension, the codemode extension for `codemode` and `codemode-deferred` servers, and the tool-search extension for `deferred` servers to the resource loader. See [Codemode and MCP](sdk.md#codemode-mcp).