feat(coding-agent): stop waiting for MCP servers on the first prompt

The first prompt waits only for servers with direct tools. Other servers
connect in the background; codemode scripts, tool_search, and the
resource tools wait for the servers they need. codemode and tool_search
are activated from the config.

Tool declarations no longer depend on connected servers: the codemode
description leaves out deferred tools, and the tool_search description
no longer lists sources. Servers are listed in an mcp_servers system
prompt section instead, set in before_agent_start from the config and
connected state, so changes are appended to the conversation.

describeNamespace() and searchTools() accept mcp__dev-radius,
mcp__dev_radius, dev-radius, and dev_radius.

closes #10212

packages/coding-agent/docs/mcp.md

@@ -58,7 +58,7 @@ Both server types support:
 - `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)).
-- `description`: what the server offers, in a sentence. The `codemode` and `tool_search` descriptions show it next to the server, so the model knows what to search for.
+- `description`: what the server offers, in a sentence. It lists the server in the system prompt (see [Control tool exposure](#control-tool-exposure)), tool search ranks the server's tools by it, and codemode's `describeNamespace()` returns it. Without it, the first line of the server instructions is used once the server connects.
 
 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.
 
@@ -87,7 +87,7 @@ Run `pi mcp list` to connect to every enabled server and print its state, tools,
 
 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.
 
-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.
+Pi connects every enabled server in the background when a session starts. A server's tools appear once it connects; the `codemode` description does not list them, so it does not change when servers connect. The first prompt waits up to 10 seconds only for servers with `direct` tools, which must be declared in its request. Other servers are waited for when they are needed: a codemode script waits for the servers it names (`mcp__<server>`) and, when it calls `searchTools()` or reads `ALL_TOOLS`, for all of them; `tool_search` and the resource tools also wait for all of them. 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.
 
 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`.
 
@@ -153,13 +153,15 @@ Each server tool is registered as `mcp__<server>__<tool>`. The server's `exposur
 
 | Exposure | Behavior | Typical use |
 |---|---|---|
-| `codemode` (default) | Callable from [`codemode`](cli.md#tools) scripts, but neither declared to the model nor listed one by one. The codemode description lists the server with its `description`; scripts find tools with `searchTools()`, `describeTool()`, or `ALL_TOOLS`. | General MCP servers, especially when scripts should combine or filter calls. |
+| `codemode` (default) | Callable from [`codemode`](cli.md#tools) scripts, but neither declared to the model nor listed in the codemode description. Scripts find tools with `searchTools()`, `describeTool()`, or `ALL_TOOLS`. | General MCP servers, especially when scripts should combine or filter calls. |
 | `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. |
 
 `codemode-deferred` is accepted as an alias for `codemode`.
 
+Servers with `codemode` or `deferred` tools are listed in the `mcp_servers` section of the system prompt, with how their tools are reached and one line from the configured `description` or, once connected, from the server instructions. Pi updates the section when a prompt starts, after waiting for servers with `direct` tools. When it changed, for example because a server connected and its summary became available, Pi appends the new section to the conversation instead of changing tool declarations, so earlier messages stay cached. `describeNamespace()` and the `namespace` option of `searchTools()` accept `mcp__dev-radius`, `mcp__dev_radius`, `dev-radius`, or `dev_radius`.
+
 Pi activates `codemode` when a server with `codemode` exposure connects. It activates `tool_search` for a server with `deferred` exposure. To make the model see a tool without searching, give it `direct` exposure with `toolExposure`.
 
 `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: