POSTFACT MCP

POSTFACT is a remote MCP server that resolves ambiguous outcomes of side-effecting actions. It determines if an action completed, failed, or remains unknown, allowing agents to decide whether to retry or verify before proceeding.

Endpoint and access

No sign-in to connect and list tools. Individual tools may still need a vendor account, credentials, or permissions; check the documented prerequisites.

Community listingStreamable HTTPNo sign-inEndpoint checked 2026-11-06Published by GSterlingPress

MCP endpoint (Streamable HTTP)

https://postfact-api-production.up.railway.app/mcp

Vendor documentation

What its tools do

1 tool, grouped by the hints the server advertises. Hints are self-declared, not verified behavior.

Read-only (1)

resolve_outcome

1 of 1 have a description · 1 of 1 declare behavior hints · 0 of 1 with parameters document them all

Checks and signals

Each line is separate evidence, not a trust score.

Passed Endpoint answered the live check · Nov 6, 2026, 3:17 PM UTC
Availability 1 of 1 checks passed in 30 days

What you can do with it

Resolve ambiguous API failures before retrying
Determine if a side-effecting action completed
Provide safe default UNKNOWN state for uncertain outcomes

Source and maintenance

Community listingRegistry 0.1.1

mcp-registry: io.github.GSterlingPress/postfact@0.1.1 Source repository Project website

Maintenance checked: Nov 6, 2026, 3:14 PM UTC

Protocol and capabilities

Server: POSTFACT 0.1.0
MCP protocol negotiated in check: 2025-11-25
Tools: 1 advertised
Resources: Not advertised
Resource templates: Not advertised
Prompts: Not advertised

Server-advertised capabilities

{
  "tools": {}
}

Server-provided instructions

Untrusted server output shown for inspection. It is not Koskamo guidance and is excluded from knowledge search.

After an ambiguous failure of a side-effecting action, call resolve_outcome BEFORE retrying. UNKNOWN means do not assume success or failure.

Tools

1 advertised

resolve_outcome — Resolve Ambiguous Side Effect

Advertised by the server during the last successful anonymous check.

Advertised read-only

Call after a side-effecting API/tool action fails ambiguously and before retrying. POSTFACT returns DONE only with affirmative completion evidence, NOT_DONE only with affirmative non-execution evidence, otherwise UNKNOWN. UNKNOWN is the safe default.

resolve_outcome input schema

{
  "type": "object",
  "properties": {
    "method": {
      "type": "string"
    },
    "status": {
      "type": "integer"
    },
    "failure": {
      "type": "string"
    },
    "evidence": {
      "type": "object",
      "properties": {
        "providerStatus": {
          "type": "string"
        },
        "resourceExists": {
          "type": "boolean"
        },
        "receiptVerified": {
          "type": "boolean"
        },
        "transactionStatus": {
          "type": "string"
        },
        "preExecutionRejection": {
          "type": "boolean"
        }
      },
      "additionalProperties": false
    },
    "requestId": {
      "type": "string"
    },
    "sideEffect": {
      "type": "boolean"
    },
    "resourceRef": {
      "type": "string"
    },
    "idempotencyKey": {
      "type": "string"
    },
    "transactionRef": {
      "type": "string"
    }
  },
  "additionalProperties": false
}

resolve_outcome annotations

{
  "readOnlyHint": true,
  "openWorldHint": false,
  "idempotentHint": true,
  "destructiveHint": false
}

Prompts

Not advertised

No prompt definitions available.

Resources

Not advertised

No resource definitions available.

90-day uptime

A lightweight connection check about every six hours, sampled on hosts with many listings. It shows the server answered, not that its tools work.

Too few checks for a percentage yet (2 of 2 answered).

2026-11-06: 1 of 1 checks answered
2026-11-07: 1 of 1 checks answered

30-day availability

Aggregated from read-only remote checks; this is not a tool-execution or security guarantee.

Successful checks: 1 of 1 (100%)
Average latency: 1006 ms
95th percentile latency: 1006 ms

Maintenance history

Public check and source-refresh events. Editorial and ownership records remain private.

Nov 6, 2026, 3:17 PM UTC · probe · passed · 1006 ms · metadata changed · 1 tool(s)

Connect from your client

Each snippet registers the same endpoint; pick the client you use.

This server is operated by the named third party. Listing and endpoint checks are not an endorsement or a security audit. Review the operator's permissions, terms, and data handling before connecting. How listings are checked and corrected.

Claude Code

Run this once in a terminal. It registers the remote server. Use --scope project to write .mcp.json for the repo.

Claude Code configuration

claude mcp add --transport http postfact-mcp https://postfact-api-production.up.railway.app/mcp

Codex

Run this once. Codex stores MCP servers in ~/.codex/config.toml (or .codex/config.toml in a trusted project).

Codex configuration

codex mcp add postfact-mcp --url https://postfact-api-production.up.railway.app/mcp

Cursor

Merge this server into .cursor/mcp.json in your project, then enable postfact-mcp in your MCP settings.

Cursor configuration

{
  "mcpServers": {
    "postfact-mcp": {
      "url": "https://postfact-api-production.up.railway.app/mcp"
    }
  }
}

Cline

Merge this into cline_mcp_settings.json (Cline → MCP Servers → Configure).

Cline configuration

{
  "mcpServers": {
    "postfact-mcp": {
      "type": "streamableHttp",
      "url": "https://postfact-api-production.up.railway.app/mcp",
      "disabled": false
    }
  }
}

VS Code

Merge this server into .vscode/mcp.json. Use MCP: List Servers to start postfact-mcp and inspect its tools.

VS Code configuration

{
  "servers": {
    "postfact-mcp": {
      "type": "http",
      "url": "https://postfact-api-production.up.railway.app/mcp"
    }
  }
}

Gemini CLI

Run this once. It writes .gemini/settings.json in the current project; pass --scope user for ~/.gemini/settings.json.

Gemini CLI configuration

gemini mcp add --transport http postfact-mcp https://postfact-api-production.up.railway.app/mcp

Claude Desktop

Open Claude Settings > Connectors > Add custom connector, enter this server URL and enable it for the conversation. This is a manual remote-connector handoff, not a desktop JSON configuration.

Claude Desktop configuration

https://postfact-api-production.up.railway.app/mcp

Windsurf

Merge this into ~/.codeium/windsurf/mcp_config.json, then refresh MCP in Cascade. Windsurf remote servers use serverUrl, not url.

Windsurf configuration

{
  "mcpServers": {
    "postfact-mcp": {
      "serverUrl": "https://postfact-api-production.up.railway.app/mcp"
    }
  }
}

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