> ## Documentation Index > Fetch the complete documentation index at: https://docs.mibyanai.com/llms.txt > Use this file to discover all available pages before exploring further. # MCP Config Reference > Reference for Mibyan MCP configuration keys, filtering semantics, and utility-tool policy This page is the compact reference companion to the main MCP docs. For conceptual guidance, see: * [MCP (Model Context Protocol)](/desktop/user-guide/features/mcp) * [Use MCP with Mibyan](/desktop/guides/use-mcp-with-mibyan) ## Root config shape ```yaml theme={null} mcp_servers: : command: "..." # stdio servers args: [] env: {} # OR url: "..." # HTTP servers headers: {} # Optional HTTP/SSE TLS settings: ssl_verify: true # bool or path to a CA bundle (PEM) client_cert: "/path/to/cert.pem" # mTLS client certificate (see below) # client_key: "/path/to/key.pem" # optional, when key lives in a separate file enabled: true timeout: 120 connect_timeout: 60 supports_parallel_tool_calls: false tools: include: [] exclude: [] resources: true prompts: true ``` ## Server keys | Key | Type | Applies to | Meaning | | - | - | - | - | | `command` | string | stdio | Executable to launch | | `args` | list | stdio | Arguments for the subprocess | | `env` | mapping | stdio | Environment passed to the subprocess | | `url` | string | HTTP | Remote MCP endpoint | | `headers` | mapping | HTTP | Headers for remote server requests | | `ssl_verify` | bool or string | HTTP | TLS verification. `true` (default) uses system CAs, `false` disables verification (insecure), or a string path to a custom CA bundle (PEM) | | `client_cert` | string or list | HTTP | mTLS client certificate. String = path to a PEM file containing cert + key. List `[cert, key]` = separate files. List `[cert, key, password]` = encrypted key | | `client_key` | string | HTTP | Path to the client private key, when `client_cert` is a string and the key is in a separate file | | `enabled` | bool | both | Skip the server entirely when false | | `timeout` | number | both | Tool call timeout in seconds (default: `300`) | | `connect_timeout` | number | both | Initial connection timeout in seconds (default: `60`) | | `protocol` | string | both | Protocol-era negotiation: `auto` (default — legacy `initialize` handshake first, falling back to the 2026-07-28 `server/discover` stateless probe when the server rejects the handshake as modern-only), `stateless` (probe `server/discover` first; one legacy retry), or `legacy` (handshake only, no fallback) | | `supports_parallel_tool_calls` | bool | both | Allow tools from this server to run concurrently | | `skip_preflight` | bool | HTTP | Bypass the fail-fast content-type probe for valid Streamable HTTP endpoints whose HEAD/GET answers a non-MCP content type (default: `false`) | | `transport` | string | HTTP | Set to `sse` to use the SSE transport instead of Streamable HTTP | | `keepalive_interval` | number | both | Liveness ping cadence in seconds (floored at 5s). HTTP defaults to `180`; set it below the server's session TTL when the server GC's idle sessions quickly. Stdio disables keepalive when omitted; set a value to opt in explicitly | | `lazy` | bool | both | Register the server's tools from the on-disk schema cache at startup and only spawn/connect it on the first tool call (default: `false`). Needs one prior live connect to fill the cache; a missing or stale entry falls back to the normal eager connect. Status surfaces show the server as `lazy` with its cached tool count until first use | | `idle_timeout_seconds` | number | stdio | Optional stdio server recycle after idle time (`0` disables). May also live under a `lifecycle:` mapping | | `max_lifetime_seconds` | number | stdio | Optional stdio server recycle after age (`0` disables). May also live under a `lifecycle:` mapping | | `tools` | mapping | both | Filtering and utility-tool policy | | `auth` | string | HTTP | Authentication method. Set to `oauth` to enable OAuth 2.1 with PKCE | | `sampling` | mapping | both | Server-initiated LLM request policy (see MCP guide) | | `elicitation` | mapping | both | Server-initiated user-input requests. `enabled` (default `true`) and `timeout` in seconds (default `300`). Form-mode requests route through the approval surface; URL-mode is declined (see MCP guide) | | `trust` | string | both | Trust tier: `full` (default) or `untrusted`. On an `untrusted` server, every write-capable tool call (any tool without a `readOnlyHint: true` annotation) requires user approval through the standard approval surface before it runs. `readOnlyHint` is a server-supplied *hint* — a lying server can at most skip approval for tools it claims are read-only, never gain extra access — so mark any server you don't fully control as `untrusted`. The same hint decides whether a call is transparently retried after the transport session expires mid-call: only `readOnlyHint: true` tools are replayed, while unannotated (write-capable) tools return an `outcome_uncertain` error — on a Streamable-HTTP server that expires idle sessions this means the first unannotated call after an idle period may fail and must be verified before re-invoking. Unrecognized values are treated as `untrusted` (fail-closed) | ## Environment variable references String values anywhere in a server entry (`env`, `headers`, `args`, `url`, …) may reference environment variables with `${VAR}` or the Cursor-style SecretRef form `${env:VAR}` — both resolve to the same variable, so MCP snippets copied from Cursor / Claude configs work unchanged: ```yaml theme={null} mcp_servers: github: command: "npx" args: ["-y", "@modelcontextprotocol/server-github"] env: GITHUB_PERSONAL_ACCESS_TOKEN: "${env:GITHUB_TOKEN}" # same as "${GITHUB_TOKEN}" ``` Values resolve from the active profile's secret scope (falling back to the process environment), so put the secret in `~/.mibyan/.env`. An unset variable keeps its literal placeholder — except in a remote server's `url` or `headers`: sending a literal `${VAR}` there is a guaranteed 401 that reads as a bad credential, so the connect fails closed instead, with the variable named in the server's status (`MCP server 'name': ${VAR} in url/headers is not set in this profile's .env or secret source`). Fix the profile's `.env` (or its secret source); the next connect attempt renders the reference afresh. ### Context variables Beyond env vars, the Cursor-style context variables are interpolated too (names are case-sensitive): | Variable | Resolves to | | - | - | | `${userHome}` | The current user's home directory | | `${workspaceFolder}` | The session workspace root (the session's terminal cwd when known, else the process cwd) | | `${workspaceFolderBasename}` | The basename of `${workspaceFolder}` | | `${pathSeparator}` / `${/}` | The OS path separator (`os.sep`) | ```yaml theme={null} mcp_servers: filesystem: command: "npx" args: ["-y", "@modelcontextprotocol/server-filesystem", "${workspaceFolder}"] env: CACHE_DIR: "${userHome}${/}.cache${/}mcp" ``` Any other `${...}` reference falls through to the env-var lookup above. ## `tools` policy keys | Key | Type | Meaning | | - | - | - | | `include` | string or list | Whitelist server-native MCP tools. Entries may be exact names or fnmatch-style globs (`*_radar_*`, `get_zones_*`) | | `exclude` | string or list | Blacklist server-native MCP tools. Same exact-name / glob semantics as `include` | | `resources` | bool-like | Enable/disable `list_resources` + `read_resource` | | `prompts` | bool-like | Enable/disable `list_prompts` + `get_prompt` | ## Filtering semantics ### `include` If `include` is set, only those server-native MCP tools are registered. ```yaml theme={null} tools: include: [create_issue, list_issues] ``` ### `exclude` If `exclude` is set and `include` is not, every server-native MCP tool except those names is registered. ```yaml theme={null} tools: exclude: [delete_customer] ``` ### Precedence If both are set, `include` wins. ```yaml theme={null} tools: include: [create_issue] exclude: [create_issue, delete_issue] ``` Result: * `create_issue` is still allowed * `delete_issue` is ignored because `include` takes precedence ## Utility-tool policy Mibyan may register these utility wrappers per MCP server: Resources: * `list_resources` * `read_resource` Prompts: * `list_prompts` * `get_prompt` ### Disable resources ```yaml theme={null} tools: resources: false ``` ### Disable prompts ```yaml theme={null} tools: prompts: false ``` ### Capability-aware registration Even when `resources: true` or `prompts: true`, Mibyan only registers those utility tools if the MCP session actually exposes the corresponding capability. So this is normal: * you enable prompts * but no prompt utilities appear * because the server does not support prompts ## `enabled: false` ```yaml theme={null} mcp_servers: legacy: url: "https://mcp.legacy.internal" enabled: false ``` Behavior: * no connection attempt * no discovery * no tool registration * config remains in place for later reuse ## Empty result behavior If filtering removes all server-native tools and no utility tools are registered, Mibyan does not create an empty MCP runtime toolset for that server. ## Example configs ### Safe GitHub allowlist ```yaml theme={null} mcp_servers: github: command: "npx" args: ["-y", "@modelcontextprotocol/server-github"] env: GITHUB_PERSONAL_ACCESS_TOKEN: "***" tools: include: [list_issues, create_issue, update_issue, search_code] resources: false prompts: false ``` ### Stripe blacklist ```yaml theme={null} mcp_servers: stripe: url: "https://mcp.stripe.com" headers: Authorization: "Bearer ***" tools: exclude: [delete_customer, refund_payment] ``` ### Resource-only docs server ```yaml theme={null} mcp_servers: docs: url: "https://mcp.docs.example.com" tools: include: [] resources: true prompts: false ``` ### TLS client certificate (mTLS) For HTTP/SSE servers that require a client certificate, set `client_cert` (and optionally `client_key`): ```yaml theme={null} mcp_servers: # Combined cert + key in a single PEM file internal_api: url: "https://mcp.internal.example.com/mcp" client_cert: "~/secrets/mcp-client.pem" # Separate cert and key files partner_api: url: "https://mcp.partner.example.com/mcp" client_cert: "~/secrets/client.crt" client_key: "~/secrets/client.key" # Encrypted key with a passphrase (3-element list form) bank_api: url: "https://mcp.bank.example.com/mcp" client_cert: ["~/secrets/client.crt", "~/secrets/client.key", "my-passphrase"] # Custom CA bundle (private CA / self-signed server) lab_api: url: "https://mcp.lab.local/mcp" ssl_verify: "~/secrets/lab-ca.pem" client_cert: "~/secrets/lab-client.pem" ``` Notes: * Paths support `~` expansion. Missing files fail fast at connect time with a server-scoped error message. * `ssl_verify: false` disables server certificate verification entirely. Don't use this with real services. * Works on both Streamable HTTP and SSE transports. ## Reloading config After changing MCP config, reload servers with: ```text theme={null} /reload-mcp ``` ## Tool naming Server-native MCP tools become: ```text theme={null} mcp____ ``` Examples: * `mcp__github__create_issue` * `mcp__filesystem__read_file` * `mcp__my_api__query_data` Utility tools follow the same prefixing pattern: * `mcp____list_resources` * `mcp____read_resource` * `mcp____list_prompts` * `mcp____get_prompt` The double-underscore delimiter (`mcp__…__…`) matches the convention used by Claude Code, Codex, and OpenCode, and disambiguates the server/tool boundary even when either component contains underscores. ### Name sanitization Any character that is not a letter, digit, or underscore (hyphens, dots, spaces, etc.) in both server names and tool names is replaced with an underscore before registration. This ensures tool names are valid identifiers for LLM function-calling APIs. For example, a server named `my-api` exposing a tool called `list-items.v2` becomes: ```text theme={null} mcp__my_api__list_items_v2 ``` Keep this in mind when writing `include` / `exclude` filters — use the **original** MCP tool name (with hyphens/dots), not the sanitized version. ## OAuth 2.1 authentication For HTTP servers that require OAuth, set `auth: oauth` on the server entry: ```yaml theme={null} mcp_servers: protected_api: url: "https://mcp.example.com/mcp" auth: oauth ``` Behavior: * Mibyan uses the MCP SDK's OAuth 2.1 PKCE flow (metadata discovery, client identification, token exchange, and refresh) * On first connect, a browser window opens for authorization * Tokens are persisted to `~/.mibyan/mcp-tokens/.json` (a named profile uses `~/.mibyan/profiles//mcp-tokens/`) and reused across sessions * Token refresh is automatic; re-authorization only happens when refresh fails * Only applies to HTTP/StreamableHTTP transport (`url`-based servers) * Under a [multiplexed gateway](/desktop/user-guide/multi-profile-gateways), an OAuth connection is never shared across profiles: each profile authenticates with its own token and opens its own connection, even when the `mcp_servers` entries are identical ### Device-code login (RFC 8628) For an authorization server advertising `device_authorization_endpoint`, explicitly choose device authorization from a terminal on the machine running Mibyan: ```bash theme={null} mibyan mcp login protected_api --flow device ``` Open the printed verification URL on any device and enter the displayed user code. Mibyan polls for approval, respects `authorization_pending` and `slow_down`, and stops on denial or expiry. No browser is launched and no callback listener is needed. `oauth.timeout` bounds the approval wait (default 300 seconds), also limited by the code's lifetime. When the server's protected-resource metadata lists several authorization servers, device login scans them in order and uses the first one whose metadata issuer matches its advertised URL and that offers the `device_code` grant (a browser-only server listed first is skipped); the only accepted difference is the path-scoped shape described under "OAuth-authenticated HTTP servers" in the MCP feature guide (a server advertised as `https://host/path` whose document at `/.well-known/oauth-authorization-server/path` names `https://host`). Set `oauth.flow: device` on the server to make `mibyan mcp login` and `mibyan mcp reauth` (including `reauth --all`) use device authorization. `login --flow browser` overrides that setting for one login; browser PKCE remains the default. Unsupported metadata produces an actionable error rather than silently falling back to a different flow. Device login requests the device and refresh grants during dynamic registration, or uses your configured `oauth.client_id`, `oauth.client_secret`, and `oauth.token_endpoint_auth_method`. The registered client must permit device authorization. The browser CIMD document is not used. `oauth.scope` is sent on the device authorization request; `oauth.user_agent` also applies to token polling. Tokens, registration, and issuer metadata stay in the active profile's MCP token store and the existing runtime refresh path reuses them after a restart. Failed device grants do not replace previously saved credentials. Initial device login is terminal-only: dashboard/browser callbacks and background reconnects do not start device authorization. Run the login command against the **same profile and host** as the gateway. An expired/rejected device grant without a usable refresh token requires another explicit login. ### Client identification: CIMD and DCR Mibyan identifies itself to authorization servers with a **Client ID Metadata Document** (CIMD), the mechanism the MCP `2026-07-28` spec adopted in place of Dynamic Client Registration. The document is published at `https://nousresearch.github.io/hermes-agent/docs/oauth/client-metadata.json`, and that URL *is* the `client_id` — the authorization server fetches it to learn Mibyan' name, logo, and permitted redirect URIs. Nothing is registered per install, and nothing is user-specific. The final choice belongs to the authorization server: the SDK sends the document URL as the `client_id` only when the server advertises `client_id_metadata_document_supported: true` in its metadata, and otherwise registers via DCR exactly as before. DCR is deprecated in the MCP spec but still what almost every deployed server uses today. #### Callback ports The document declares a fixed set of loopback redirect URIs, and the spec requires the redirect URI in an authorization request to be an *exact string match* against one of them — so a CIMD flow cannot use the random high port Mibyan normally picks. Mibyan therefore pins the callback to one of ports `27890`–`27894`. That pin has to be chosen before the server's capabilities are known, because the redirect URI is fixed at the start of the flow while the server's metadata only arrives partway through. So Mibyan pins the port for any flow that *could* end up using CIMD, and reverts to a random port for the rest: * A server Mibyan has connected to before, whose cached metadata does not advertise CIMD, keeps the random port it has always used. * A server Mibyan has never reached gets a pinned port on that first login, since guessing is the only way CIMD can ever be used. * Anything that would move the callback elsewhere reverts too: a pre-registered `oauth.client_id`, an `oauth.client_secret`, a custom `oauth.client_name` or `oauth.token_endpoint_auth_method`, an `oauth.redirect_uri` or `oauth.redirect_port` override, a dashboard- or desktop-driven login, an existing client registration on disk, or all five ports being held by other processes. Each pinned port is bound as soon as it is chosen and held until the browser redirect arrives, so two concurrent logins — a second profile, or another server in the same process — cannot land on the same listener. #### When a server rejects the document If a server fetches the document and refuses it at the *token* endpoint (`invalid_client`), Mibyan logs the rejection, records it under `~/.mibyan/mcp-tokens/.cimd-off`, and uses DCR for that server from then on. A server that cannot fetch or validate the document at all aborts at the *authorization* endpoint instead, before any redirect happens. There is no signal Mibyan can observe there, so the browser shows an invalid-client error and the login times out after five minutes. The timeout message names the document and points at `cimd: false`. Running `mibyan mcp login ` clears the recorded rejection, so a corrected document gets another chance. #### Optional per-server keys ```yaml theme={null} mcp_servers: protected_api: url: "https://mcp.example.com/mcp" auth: oauth oauth: client_metadata_url: "https://example.com/my-cimd.json" # self-hosted document cimd: false # force DCR user_agent: "My-MCP-Client/1.0" # token-request User-Agent ``` `client_metadata_url` must be an HTTPS URL with a path (no bare origin, no fragment, no userinfo, no `.`/`..` segments) that returns `200` and `Content-Type: application/json` with **no redirect** — authorization servers are forbidden from following redirects when fetching it. Mibyan still pins its callback to the same `27890`–`27894` range, so a self-hosted document must declare all ten loopback URIs (`http://127.0.0.1:/callback` and `http://localhost:/callback` for each port), and its `client_id` must be its own URL. `user_agent` replaces the default `User-Agent` on **token-endpoint requests only** (authorization-code exchange, refresh and the device-flow token poll). Without it Mibyan sends `Mibyan-Agent/` — never a header-less request, which WAF-fronted authorization servers answer with `403`. It never applies to MCP traffic, and no other token-request headers are configurable. Empty or null values are ignored. A failed exchange reports the status plus a short, redacted excerpt of the error body (a WAF's "Request blocked" page vs the issuer's `invalid_grant`), so the cause is visible without packet captures. `mibyan mcp login` clears the stale grant and client registration before re-authorizing but keeps the cached authorization-server metadata, so the announced authorize URL stays the discovered one even when the metadata document cannot be re-fetched. OAuth discovery and dynamic-client-registration requests (the `/.well-known/...` metadata documents and the `registration_endpoint` POST) always carry `User-Agent: Mibyan-Agent/`. The MCP SDK builds those requests without any client default headers, and WAF-fronted authorization servers answer a header-less request with `403` — the metadata document then looks unreadable, registration falls back to a guessed `/register` on the MCP host, and the login fails with `Registration failed: 404`. When every metadata fetch does fail, the error now leads with those statuses (`Could not read authorization-server metadata (403 from https://…/.well-known/oauth-authorization-server; …)`) before the registration fallback's own error. ## Add to Mibyan link MCP vendors and docs can offer a one-click **"Add to Mibyan"** button that opens the Mibyan desktop app with a pre-filled server config, mirroring Cursor's `cursor://anysphere.cursor-deeplink/mcp/install` scheme: ```text theme={null} mibyan://mcp/install?name=NAME&config=BASE64 ``` * `name` — the server name. Must match `^[A-Za-z0-9._-]{1,64}$`. * `config` — the server config object as **base64url-encoded JSON** (standard base64 is also accepted). The decoded JSON must be an object with either a string `url` field (`http://`/`https://` only) or a string `command` field, and may carry any of the server keys documented above. Payloads over 32KB are rejected. Example (JavaScript): ```js theme={null} const config = { url: 'https://mcp.example.com/mcp' } const link = `mibyan://mcp/install?name=example&config=${btoa(JSON.stringify(config)) .replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '')}` ``` Opening the link never installs anything by itself: the desktop app shows a confirmation dialog with the server name and the full pretty-printed config (with an extra caution for `command`-based servers, which run a local process), and the user must explicitly confirm. Existing server names are never overwritten — the user is asked to rename or cancel. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.