> ## Documentation Index > Fetch the complete documentation index at: https://docs.formal.ai/llms.txt > Use this file to discover all available pages before exploring further. # PostHog > Query PostHog analytics, insights, experiments, and event definitions. Data Publisher: PostHog Route PostHog MCP traffic through Formal to control and log what AI agents do in PostHog: * **Block** risky tools, such as `query-run`. * **Mask** sensitive data in tool results, such as secrets and API keys in `query-run` responses. * **Keep credentials at the Connector**, so users and agents never see PostHog tokens. * **Log** every tool call with the user, the MCP client and its parameters. Cloud agents Laptop / VM Endpoint [https://mcp.posthog.com/mcp](https://mcp.posthog.com/mcp) Connector ![](https://docs.formal.ai/static/brands/mcp/posthog.svg) ## 0. Prepare your Connector The Connector needs an MCP listener and a hostname with wildcard DNS and TLS. Set them up once by following [Deploy the Connector](https://docs.formal.ai/docs/guides/core-concepts/connectors/mcp-gateway.md#deploy-the-connector). Every MCP server reuses them. ## 1. Add PostHog MCP server to your Resources > [tab] UI > > 1. Open the [Admin Catalog](https://app.formal.ai/catalog) and click **Add MCP**. > 2. Select the **PostHog** template. > 3. Enter a DNS-label **Name**, such as `posthog`. > 4. Choose the **Space** containing your Connector, such as `default`. > 5. Configure upstream authentication as described below, then save. > > If no Connector is in the selected Space, the **Configuration** tab shows **MCP clients can't connect directly yet**. > The reason reads: `No Connector is in this server's Space.` > > Adding PostHog to the Admin Catalog > [tab] Terraform > > Set `space_id` to the ID of the Space containing your Connector. > > ```hcl theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > resource "formal_resource" "posthog" { > name = "posthog" > technology = "mcp" > hostname = "mcp.posthog.com" > space_id = "" > native_users_v3_enabled = true > port = 443 > tags = { > "mcp-endpoint" = "/mcp" > } > } > > resource "formal_resource_oauth_settings" "posthog" { > resource_id = formal_resource.posthog.id > } > ``` > [tab] Pulumi > > Set `spaceId` to the ID of the Space containing your Connector. > > ```ts theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > import * as formal from "@formalco/pulumi"; > > const resource = new formal.Resource("mcp", { > name: "posthog", > technology: "mcp", > hostname: "mcp.posthog.com", > port: 443, > spaceId: "", > tags: { "mcp-endpoint": "/mcp" }, > nativeUsersV3Enabled: true, > }); > > new formal.ResourceOauthSettings("mcpOAuth", { > resourceId: resource.id, > }); > ``` > [tab] API > > Create a Resource with the MCP endpoint and its Space ID. > > ```bash theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > export FORMAL_API_KEY="" > RESOURCE_RESPONSE=$(curl --fail --silent --show-error \ > --request POST \ > https://api.formal.ai/core.v1.ResourceService/CreateResource \ > --header "x-api-key: ${FORMAL_API_KEY}" \ > --header "Content-Type: application/json" \ > --data-binary @- < { > "name": "posthog", > "hostname": "mcp.posthog.com", > "port": 443, > "technology": "mcp", > "spaceId": "", > "tags": [ > { > "key": "mcp-endpoint", > "value": "/mcp" > } > ] > } > JSON > ) > RESOURCE_ID=$(printf '%s' "${RESOURCE_RESPONSE}" | jq -r '.resource.id') > curl --fail --silent --show-error \ > --request POST \ > https://api.formal.ai/core.v1.ResourceService/CreateResourceOAuthSettings \ > --header "x-api-key: ${FORMAL_API_KEY}" \ > --header "Content-Type: application/json" \ > --data-binary @- < { > "resourceId": "${RESOURCE_ID}" > } > JSON > ``` ## 2. Setup Authentication > [tab] Linked Accounts (Recommended) > > Each user links their own PostHog account once in the Employee Catalog, and the Connector sends that user's token to PostHog. > > ![Linked Accounts selected under How does Formal authenticate to this resource?](https://mintcdn.com/formal/vzPMpIcsF4BYmdx8/assets/images/mcp-servers/auth-linked-accounts.png?fit=max\&auto=format\&n=vzPMpIcsF4BYmdx8\&q=85\&s=dc448db2a373faa6e1bf49fd5ffaf7c4) > > Under **OAuth app**, keep **Formal's App**. > > #### Formal's App (default) > > PostHog supports [Client ID Metadata Documents](https://modelcontextprotocol.io/specification/2026-07-28/basic/authorization/client-registration#client-id-metadata-documents), so you register nothing. > Users see Formal on PostHog's consent screen. > [tab] Shared Credentials > > An administrator stores one PostHog token in Formal, and the Connector sends it on every user's requests without showing it to them. > > ![Shared Credentials selected under How does Formal authenticate to this resource?](https://mintcdn.com/formal/R-3CwVgs8IU6liji/assets/images/mcp-servers/auth-shared-credentials.png?fit=max\&auto=format\&n=R-3CwVgs8IU6liji\&q=85\&s=91032e202518088292ee1cf39451b9ef) > > PostHog's MCP endpoint accepts a [Personal API key](https://posthog.com/docs/model-context-protocol/faq#using-an-api-key-instead-of-oauth) as a Bearer token. > Create one at [app.posthog.com/settings/user-api-keys?preset=mcp\_server](https://app.posthog.com/settings/user-api-keys?preset=mcp_server). > Use the MCP Server preset and restrict project access; reduce permissions to the read operations you need. > > 1. Open this server from the [Admin Catalog](https://app.formal.ai/catalog). > 2. Select **Configuration**, then **Authentication**. > 3. Choose **Shared Credentials**, then select **Add credential**. > 4. Enter the credential, make it the default, and select **Save authentication**. > > See [Native Users](https://docs.formal.ai/docs/guides/core-concepts/resources/native-users.md). > > For HTTP Bearer authentication, enter the raw token. The Connector adds the `Bearer ` prefix. > > In the Terraform tab, set `native_users_v3_enabled = true` on the Resource and `upstream_oauth_mode = "none"` on its OAuth settings. > > ```hcl theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > variable "mcp_shared_credential" { > type = string > sensitive = true > } > > resource "formal_native_user_v3" "mcp_shared_credential" { > resource_id = formal_resource.posthog.id > label = "shared-credential" > > http_bearer { > header = "Authorization" > token { > literal_wo = var.mcp_shared_credential > literal_wo_version = 1 > } > } > } > > resource "formal_resource_native_user_selection" "mcp_shared_credential" { > resource_id = formal_resource.posthog.id > cel = "\"${formal_native_user_v3.mcp_shared_credential.id}\"" > } > ``` > [tab] Pass Through > > Each user sends their own PostHog sign-in or token from their MCP client, and Formal forwards it unchanged without storing it. > > ![Pass Through selected under How does Formal authenticate to this resource?](https://mintcdn.com/formal/R-3CwVgs8IU6liji/assets/images/mcp-servers/auth-pass-through.png?fit=max\&auto=format\&n=R-3CwVgs8IU6liji\&q=85\&s=c14ae61de2dba8b567626cba03aae2cf) > > Nothing in the request identifies the Formal user. Formal attributes these requests only when they come through the [Formal Endpoint](https://docs.formal.ai/docs/guides/core-concepts/connectors/mcp-gateway.md#identity-headers). Pass-through servers have no Connector address, so cloud agents can't use them. > > For OAuth, each MCP client signs in to PostHog itself. ## 3. Route Endpoint traffic Auth is managed at the Connector level when you use Linked Accounts or Shared Credentials, so the Endpoint needs to forward the MCP traffic to it. Laptops and VMs with the Formal Endpoint keep using `https://mcp.posthog.com/mcp`, and a network rule sends that traffic to the Connector. > [tab] UI > > 1. Go to [Network Rules](https://app.formal.ai/network-rules) and create a rule named `posthog-mcp`. > 2. Paste this expression, set the rule to **Active**, then save: > > ```javascript theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > { > "condition": { > "pre_tcp": process.is_agent, > // Every MCP server added to Formal: process.is_agent && resource.technology == "mcp" > "pre_tls": process.is_agent && hostname == "mcp.posthog.com", > "post_tls": true > }, > "outputs": { > "forward_to_connector": true > } > } > ``` > [tab] Terraform > > ```hcl theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > resource "formal_network_rule" "posthog_mcp" { > name = "posthog-mcp" > description = "Forward PostHog MCP traffic from agents to the Connector" > status = "active" > > # Every MCP server added to Formal: set pre_tls to process.is_agent && resource.technology == "mcp" > cel_expression = <<-EOT > { > "condition": { > "pre_tcp": process.is_agent, > "pre_tls": process.is_agent && hostname == "mcp.posthog.com", > "post_tls": true > }, > "outputs": { > "forward_to_connector": true > } > } > EOT > } > ``` > [tab] Pulumi > > ```ts theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > import * as formal from "@formalco/pulumi"; > > new formal.NetworkRule("posthogMcp", { > name: "posthog-mcp", > description: "Forward PostHog MCP traffic from agents to the Connector", > status: "active", > // Every MCP server added to Formal: set pre_tls to process.is_agent && resource.technology == "mcp" > celExpression: ` > { > "condition": { > "pre_tcp": process.is_agent, > "pre_tls": process.is_agent && hostname == "mcp.posthog.com", > "post_tls": true > }, > "outputs": { > "forward_to_connector": true > } > } > `, > }); > ``` > [tab] API > > ```bash theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > export FORMAL_API_KEY="" > # Every MCP server added to Formal: set pre_tls to process.is_agent && resource.technology == "mcp" > CEL_EXPRESSION=$(cat <<'CEL' > { > "condition": { > "pre_tcp": process.is_agent, > "pre_tls": process.is_agent && hostname == "mcp.posthog.com", > "post_tls": true > }, > "outputs": { > "forward_to_connector": true > } > } > CEL > ) > jq -n --arg cel "${CEL_EXPRESSION}" '{ > name: "posthog-mcp", > description: "Forward PostHog MCP traffic from agents to the Connector", > status: "active", > celExpression: $cel > }' | curl --fail --silent --show-error \ > --request POST \ > https://api.formal.ai/core.v1.DesktopService/CreateDesktopRoutingRule \ > --header "x-api-key: ${FORMAL_API_KEY}" \ > --header "Content-Type: application/json" \ > --data-binary @- > ``` The rule matches [known agents](https://docs.formal.ai/docs/guides/network-rules.md#known-agent-identities) only. See [Identity headers](https://docs.formal.ai/docs/guides/core-concepts/connectors/mcp-gateway.md#identity-headers). Cloud agents such as Claude, ChatGPT and Cursor Cloud Agents don't run the Endpoint. Point them at this server's Connector address, `https://posthog./mcp`. Find it in the [Admin Catalog](https://app.formal.ai/catalog): open PostHog, then copy **Connector address** on the **Configuration** tab. ## 4. Create policies ### Tools The Admin Catalog lists these tools for PostHog: | Tool | Description | | - | - | | `query-run` | Run an analytics query. | | `query-generate-hogql-from-question` | Write a HogQL query from a question. | | `insight-query` | Run a saved insight's query. | | `experiment-get-all` | List experiments. | | `experiment-results-get` | Get an experiment's results. | | `event-definitions-list` | List event definitions. | | `actions-get-all` | List actions. | | `alerts-list` | List alerts. | | `annotations-list` | List annotations. | ### Policies examples > [tab] Mask a tool's output > > This policy replaces email addresses in results returned by `query-run`, `insight-query`, and `annotations-list`. > > ```rego theme={"languages":{"custom":["/languages/cel.json","/languages/rego.json"]}} > package formal.v2 > > import future.keywords.if > import future.keywords.in > > email_pattern := `[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}` > > response := { > "action": "rewrite", > "body": regex.replace(input.http.body, email_pattern, "[REDACTED-EMAIL]"), > "reason": "Mask emails in PostHog results", > } if { > input.resource.name == "posthog" > input.mcp.tool_name in {"query-run", "insight-query", "annotations-list"} > regex.match(email_pattern, input.http.body) > } > ``` See [MCP resources](https://docs.formal.ai/docs/guides/policies/evaluation.md#mcp-resources) for the `input.mcp` fields and [Rewrite Action](https://docs.formal.ai/docs/guides/policies/enforcement.md#rewrite-action) for body rewrites. ## 5. Check the logs Open [Logs](https://app.formal.ai/logs) and search for `resource.name:posthog`. Each PostHog tool call is one `request` log with the user, the MCP client and the tool. Open a log to see its tool parameters and the policies it triggered. A masked search shows the rewrite policy. PostHog tool calls in Logs, including a masked response and a blocked write See [Logs](https://docs.formal.ai/docs/guides/observability/logs.md) for search syntax and filters. ## Troubleshooting > [accordion] The agent says Formal has no current sign-in > > The agent relays: `Formal has no current posthog sign-in for you. Link or re-link your posthog account in Formal…` > > **Cause:** The user never linked PostHog, or the token expired and couldn't be refreshed. > > **Fix:** Open the server in the [Employee Catalog](https://catalog.formal.ai) and link PostHog again. > [accordion] The agent says PostHog rejected your credentials > > The agent relays: `posthog rejected your credentials. Link or re-link your posthog account in Formal…` > > **Cause:** PostHog no longer accepts the linked token, for example after the user revoked access in PostHog. > > **Fix:** Link PostHog again from the [Employee Catalog](https://catalog.formal.ai). > > With Shared Credentials, the message asks the user to contact an administrator. Replace the token in the server's **Shared Credentials**. > [accordion] Laptop traffic doesn't appear in Logs > > **Cause:** The Endpoint isn't running, or the network rule doesn't match the client. > > **Fix:** Check the Endpoint is connected. The rule above only matches [known agents](https://docs.formal.ai/docs/guides/network-rules.md#known-agent-identities). Other clients, such as a browser, reach PostHog directly unless the rule also matches them. See [Network rules](https://docs.formal.ai/docs/guides/network-rules.md). > [accordion] MCP clients can't connect directly yet > > **Cause:** The **Configuration** tab lists the reason, most often `No Connector is in this server's Space.` > > **Fix:** Edit the server and choose the Space containing its Connector. ## Next Steps > [card] [MCP Gateway](https://docs.formal.ai/docs/guides/core-concepts/connectors/mcp-gateway.md) > > Configure Connector routing and downstream access > [card] [All MCP servers](https://docs.formal.ai/docs/guides/core-concepts/connectors/mcp-servers/index.md) > > Browse every MCP server template This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.