HoldKit MCP

HoldKit provides idempotency keys, distributed locks, timers, and inboxes for AI agents communicating over the Model Context Protocol (MCP). It enables reliable agent interactions by managing state, preventing duplicate actions, and handling asynchronous messaging without requiring payment integrations.

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.

Vendor evidenceStreamable HTTPNo sign-inEndpoint checked 2026-11-01Operated by PeerFoundry

MCP endpoint (Streamable HTTP)

https://holdkit.peerfoundry.ai/mcp

Vendor documentation

What you can do with it

Create idempotency keys to prevent duplicate agent actions
Manage distributed locks for resource synchronization
Set and cancel timers for delayed agent tasks
Send and receive messages via agent inboxes

Source and maintenance

Vendor evidenceRegistry 0.1.0

mcp-registry: ai.peerfoundry/holdkit@0.1.0 Project website

Protocol and capabilities

Server: holdkit 0.1.0
MCP protocol: 2025-06-18
Tools: 14 advertised
Resources: Not advertised
Resource templates: Not advertised
Prompts: Not advertised

Server-advertised capabilities

{
  "tools": {
    "listChanged": true
  }
}

Tools

14 advertised

keys.create — Create caller key

Advertised by the server during the last successful anonymous check.

Mint a pf_ caller key bound to one HoldKit namespace.

keys.create input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "properties": {}
}

keys.create annotations

{
  "readOnlyHint": false,
  "destructiveHint": false
}

inbox.create — Create inbox

Advertised by the server during the last successful anonymous check.

Create an inbox. Returns webhook and A2A URLs.

inbox.create input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "properties": {}
}

inbox.create annotations

{
  "readOnlyHint": false,
  "destructiveHint": false
}

inbox.poll — Poll inbox

Advertised by the server during the last successful anonymous check.

Advertised read-only

Read inbox events after a cursor.

inbox.poll input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "inbox_id"
  ],
  "properties": {
    "limit": {
      "type": "integer",
      "maximum": 50,
      "exclusiveMinimum": 0
    },
    "cursor": {
      "type": "integer",
      "maximum": 9007199254740991,
      "minimum": 0
    },
    "inbox_id": {
      "type": "string"
    }
  }
}

inbox.poll annotations

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

inbox.ack — Ack inbox

Advertised by the server during the last successful anonymous check.

Advertised destructive

Mark inbox events done.

inbox.ack input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "inbox_id",
    "event_ids"
  ],
  "properties": {
    "inbox_id": {
      "type": "string"
    },
    "event_ids": {
      "type": "array",
      "items": {
        "type": "string"
      },
      "maxItems": 50
    }
  }
}

inbox.ack annotations

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

inbox.wait — Wait inbox

Advertised by the server during the last successful anonymous check.

Advertised read-only

Poll an inbox. block_ms is accepted and capped at 0 in this MVP, so the call returns current events.

inbox.wait input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "inbox_id"
  ],
  "properties": {
    "cursor": {
      "type": "integer",
      "maximum": 9007199254740991,
      "minimum": 0
    },
    "block_ms": {
      "type": "integer",
      "maximum": 25000,
      "minimum": 0
    },
    "inbox_id": {
      "type": "string"
    }
  }
}

inbox.wait annotations

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

timer.set — Set timer

Advertised by the server during the last successful anonymous check.

Schedule a durable timer. Delivery URLs must be public https.

timer.set input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "delay_s",
    "payload"
  ],
  "properties": {
    "url": {
      "type": "string"
    },
    "delay_s": {
      "type": "integer",
      "maximum": 9007199254740991,
      "minimum": 0
    },
    "payload": {
      "type": "string"
    },
    "inbox_id": {
      "type": "string"
    }
  }
}

timer.set annotations

{
  "readOnlyHint": false,
  "destructiveHint": false
}

timer.cancel — Cancel timer

Advertised by the server during the last successful anonymous check.

Advertised destructive

Cancel a timer.

timer.cancel input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "timer_id"
  ],
  "properties": {
    "timer_id": {
      "type": "string"
    }
  }
}

timer.cancel annotations

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

lock.acquire — Acquire lock

Advertised by the server during the last successful anonymous check.

Take a lease lock. Returns a fencing token.

lock.acquire input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "name",
    "ttl_s"
  ],
  "properties": {
    "name": {
      "type": "string"
    },
    "owner": {
      "type": "string"
    },
    "ttl_s": {
      "type": "integer",
      "maximum": 3600,
      "exclusiveMinimum": 0
    }
  }
}

lock.acquire annotations

{
  "readOnlyHint": false,
  "destructiveHint": false
}

lock.release — Release lock

Advertised by the server during the last successful anonymous check.

Advertised destructive

Release a lock with its fencing token.

lock.release input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "name",
    "fencing"
  ],
  "properties": {
    "name": {
      "type": "string"
    },
    "fencing": {
      "type": "integer",
      "maximum": 9007199254740991,
      "minimum": -9007199254740991
    }
  }
}

lock.release annotations

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

idem.begin — Begin idempotency

Advertised by the server during the last successful anonymous check.

Start an idempotency key or return the prior outcome. fingerprint is a hex hash.

idem.begin input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "key",
    "scope",
    "fingerprint"
  ],
  "properties": {
    "key": {
      "type": "string",
      "maxLength": 200,
      "minLength": 1
    },
    "scope": {
      "type": "string",
      "maxLength": 64,
      "minLength": 1
    },
    "ttl_s": {
      "type": "integer",
      "maximum": 86400,
      "minimum": 1
    },
    "fingerprint": {
      "type": "string",
      "pattern": "^[a-f0-9]{32,128}$"
    }
  }
}

idem.begin annotations

{
  "readOnlyHint": false,
  "destructiveHint": false
}

idem.commit — Commit idempotency

Advertised by the server during the last successful anonymous check.

Store the outcome reference for an idempotency key. scope (max 64) and owner are optional. When owner is omitted, the caller key hash is sent.

idem.commit input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "key",
    "result_ref"
  ],
  "properties": {
    "key": {
      "type": "string"
    },
    "owner": {
      "type": "string"
    },
    "scope": {
      "type": "string",
      "maxLength": 64
    },
    "result_ref": {
      "type": "string"
    }
  }
}

idem.commit annotations

{
  "readOnlyHint": false,
  "destructiveHint": false
}

kv.get — Get value

Advertised by the server during the last successful anonymous check.

Advertised read-only

Read a small value.

kv.get input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "key"
  ],
  "properties": {
    "key": {
      "type": "string"
    }
  }
}

kv.get annotations

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

kv.set — Set value

Advertised by the server during the last successful anonymous check.

Write a small value with a TTL. Emails and card numbers are rejected.

kv.set input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "key",
    "value",
    "ttl_s"
  ],
  "properties": {
    "key": {
      "type": "string"
    },
    "ttl_s": {
      "type": "integer",
      "maximum": 9007199254740991,
      "exclusiveMinimum": 0
    },
    "value": {
      "type": "string"
    }
  }
}

kv.set annotations

{
  "readOnlyHint": false,
  "destructiveHint": false
}

kv.delete — Delete value

Advertised by the server during the last successful anonymous check.

Advertised destructive

Delete a value.

kv.delete input schema

{
  "type": "object",
  "$schema": "https://json-schema.org/draft/2020-12/schema",
  "required": [
    "key"
  ],
  "properties": {
    "key": {
      "type": "string"
    }
  }
}

kv.delete annotations

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

Prompts

Not advertised

No prompt definitions available.

Resources

Not advertised

No resource definitions available.

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: 294 ms
95th percentile latency: 294 ms

Maintenance history

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

Nov 1, 2026, 7:43 AM UTC · probe · passed · 294 ms · metadata changed · 14 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 holdkit-mcp https://holdkit.peerfoundry.ai/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 holdkit-mcp --url https://holdkit.peerfoundry.ai/mcp

Cursor

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

Cursor configuration

{
  "mcpServers": {
    "holdkit-mcp": {
      "url": "https://holdkit.peerfoundry.ai/mcp"
    }
  }
}

Cline

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

Cline configuration

{
  "mcpServers": {
    "holdkit-mcp": {
      "type": "streamableHttp",
      "url": "https://holdkit.peerfoundry.ai/mcp",
      "disabled": false
    }
  }
}

VS Code

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

VS Code configuration

{
  "servers": {
    "holdkit-mcp": {
      "type": "http",
      "url": "https://holdkit.peerfoundry.ai/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 holdkit-mcp https://holdkit.peerfoundry.ai/mcp

Claude Desktop

Merge this into claude_desktop_config.json (macOS: ~/Library/Application Support/Claude/, Windows: %APPDATA%\Claude\), then restart Claude Desktop.

Claude Desktop configuration

{
  "mcpServers": {
    "holdkit-mcp": {
      "url": "https://holdkit.peerfoundry.ai/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": {
    "holdkit-mcp": {
      "serverUrl": "https://holdkit.peerfoundry.ai/mcp"
    }
  }
}

Let your agent find its tools

Find servers like HoldKit MCP from your agent. Add Koskamo once to search the index for endpoints, access requirements, and client setup. Public discovery needs no key.

Connect Koskamo Explore workflows

See all 6,828

Do you run HoldKit MCP?

Prove ownership with a DNS record, a well-known file, or your Official MCP Registry entry, and your edits publish immediately. Proofs are re-checked weekly; admins can still hide or remove a listing.

Claim this listing

HoldKit MCP

Endpoint and access

What you can do with it

Source and maintenance

Protocol and capabilities

Tools

Prompts

Resources

30-day availability

Maintenance history

Connect from your client

Claude Code

Codex

Cursor

Cline

VS Code

Gemini CLI

Claude Desktop

Windsurf

Let your agent find its tools

Other developer tools servers

Do you run HoldKit MCP?