> ## Documentation Index > Fetch the complete documentation index at: https://docs.domesystems.ai/llms.txt > Use this file to discover all available pages before exploring further. # Guards > Author content-inspection Filters and assign them to model and MCP server connections from an MCP client Author Filters — content-inspection Guards — and bind them to model or MCP server (tool) connections. Text Filters attach to model connections; JSON Filters attach to tool connections. All Guards tools require workspace context. Editing a Filter deploys a new active version. Assigned connections pick it up on the next gateway sync — history is preserved and can be rolled back to. A Filter whose stored config fails to decode blocks its `(connection, direction)` until the config is fixed — the gateway never relays unfiltered traffic. ## List filters `dome_guards_list_filters` List the workspace's Filters, each with its active version and config. | Parameter | Type | Required | Description | | --------- | ---- | -------- | ------------- | | — | — | — | No parameters | ## Get filter `dome_guards_get_filter` Fetch one Filter's active version and config. | Parameter | Type | Required | Description | | --------- | ------ | -------- | ------------------- | | `filter` | string | Yes | Filter name or UUID | ## List filter versions `dome_guards_list_filter_versions` List a Filter's version history, newest first. Rollback-produced versions cite their source version id. | Parameter | Type | Required | Description | | --------- | ------ | -------- | ------------------- | | `filter` | string | Yes | Filter name or UUID | ## Create filter `dome_guards_create_filter` Create a Filter — its first active version. Supply the config via the convenience params (text-only) or `config_json` (any kind). | Parameter | Type | Required | Description | | ------------------- | --------------- | --------------------------------------- | -------------------------------------------------------------------------- | | `name` | string | Yes | Filter name (workspace-scoped) | | `description` | string | No | One-line description | | `redact_substrings` | array of string | No | Substrings to redact in matched responses (text) | | `block_substrings` | array of string | No | Substrings that block the response on a match (text) | | `redact_ssn` | bool | No | Redact US SSN patterns (text) | | `block_ssn` | bool | No | Block the response on an SSN match (text) | | `config_json` | string | For JSON Filters, or full-fidelity text | Protojson `dome.guards.v1.FilterConfig`. Overrides the convenience params. | The convenience params build at most two components — a `redact` component and a `block` component, redact ordered first — and only produce text Filters. Pass `config_json` to author a JSON Filter or a multi-component text chain. ### JSON Filter config ```json theme={"system"} { "json": { "components": [ { "field_actions": [ { "matcher": { "key": "ssn" }, "action": "FILTER_ACTION_OMIT" }, { "matcher": { "key": "email" }, "action": "FILTER_ACTION_REDACT" }, { "matcher": { "key": "card" }, "action": "FILTER_ACTION_BLOCK" } ] } ] } } ``` `BLOCK` withholds the whole message. `OMIT` removes the key and value. `REDACT` rewrites the value with a redaction sentinel. When multiple actions target the same key: `BLOCK` > `OMIT` > `REDACT`. ## Update filter `dome_guards_update_filter` Edit metadata in place (`new_name`, `description`), or deploy a new active version by passing any config param. History is preserved. | Parameter | Type | Required | Description | | ------------------------------------------------------------------------------------- | ------ | -------- | --------------------------------------------- | | `filter` | string | Yes | Filter name or UUID | | `new_name` | string | No | New name for the logical Filter | | `description` | string | No | New description | | `redact_substrings` / `block_substrings` / `redact_ssn` / `block_ssn` / `config_json` | — | No | Any config param deploys a new active version | Pass at least one of `new_name`, `description`, or a config param. ## Rollback filter `dome_guards_rollback_filter` Roll a Filter back to an earlier version. The target version's config is copied forward into a new active version. | Parameter | Type | Required | Description | | ------------ | ------ | -------- | ------------------------------ | | `filter` | string | Yes | Filter name or UUID | | `to_version` | number | Yes | Version number to roll back to | ## Delete filter `dome_guards_delete_filter` Hard-delete a Filter and its connection assignments. | Parameter | Type | Required | Description | | --------- | ------ | -------- | ------------------- | | `filter` | string | Yes | Filter name or UUID | ## List model connection filters `dome_model_guards_filters_list` List the text Filters assigned to a model connection, in chain order, grouped by direction. | Parameter | Type | Required | Description | | ------------ | ------ | -------- | --------------------- | | `connection` | string | Yes | Model connection name | ## Set model connection filters `dome_model_guards_filters_set` Replace the entire ordered Filter chain for one direction on a model connection. Only `text`-kind Filters may be assigned. `response` filters completions the agent receives. `request` filters the outbound prompt before dispatch to the model provider — a match can redact or block the call. | Parameter | Type | Required | Description | | ------------ | --------------- | -------- | ----------------------------------------------------- | | `connection` | string | Yes | Model connection name | | `direction` | string | Yes | `response` or `request` | | `filters` | array of string | Yes | Ordered Filter names or UUIDs; empty clears the chain | ## List tool connection filters `dome_tool_guards_filters_list` List the JSON Filters assigned to an MCP server (tool) connection, in chain order, grouped by direction. | Parameter | Type | Required | Description | | ------------ | ------ | -------- | -------------------------- | | `connection` | string | Yes | MCP server connection name | ## Set tool connection filters `dome_tool_guards_filters_set` Replace the entire ordered Filter chain for one direction on a tool connection. Only `json`-kind Filters may be assigned. `request` filters run over tool arguments **before** the call reaches the upstream MCP server — matched fields are redacted or omitted, or the whole call is blocked. `response` filters run over the tool result before the agent sees it. | Parameter | Type | Required | Description | | ------------ | --------------- | -------- | ----------------------------------------------------- | | `connection` | string | Yes | MCP server connection name | | `direction` | string | Yes | `response` or `request` | | `filters` | array of string | Yes | Ordered Filter names or UUIDs; empty clears the chain | ## Next steps Create and assign Filters from Govern. Catalogs cover windows and path syntax: * [Configure Guards](/govern/guards) * [Guards](/concepts/controls/guards) concept * [Guards](/reference/controls/guards) reference