fleet-memory/hindsight-docs/versioned_docs/version-0.4/developer/mcp-server.md

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MCP Server

Hindsight includes a built-in Model Context Protocol (MCP) server that allows AI assistants to store and retrieve memories directly.

Access

The MCP server is enabled by default and mounted at /mcp on the API server. Each memory bank has its own MCP endpoint:

http://localhost:8888/mcp/{bank_id}/

For example, to connect to the memory bank alice:

http://localhost:8888/mcp/alice/

To disable the MCP server, set the environment variable:

export HINDSIGHT_API_MCP_ENABLED=false

Authentication

By default, the MCP endpoint is open (no authentication required).

To enable authentication, configure the API key tenant extension:

export HINDSIGHT_API_TENANT_EXTENSION=hindsight_api.extensions.builtin.tenant:ApiKeyTenantExtension
export HINDSIGHT_API_TENANT_API_KEY=your-secret-key

When authentication is enabled, include your API key in the Authorization header:

Claude Code

claude mcp add --transport http hindsight http://localhost:8888/mcp \
  --header "Authorization: Bearer your-secret-key" \
  --header "X-Bank-Id: my-bank"

Claude Desktop

Add to ~/.claude_desktop_config.json:

{
  "mcpServers": {
    "hindsight": {
      "url": "http://localhost:8888/mcp",
      "headers": {
        "Authorization": "Bearer your-secret-key",
        "X-Bank-Id": "my-bank"
      }
    }
  }
}

Direct HTTP Request

curl -X POST http://localhost:8888/mcp \
  -H "Authorization: Bearer your-secret-key" \
  -H "X-Bank-Id: my-bank" \
  -H "Content-Type: application/json" \
  -H "Accept: application/json, text/event-stream" \
  -d '{"jsonrpc": "2.0", "method": "tools/list", "id": 1}'

If the key is missing or invalid, requests will receive a 401 Unauthorized response.

Bank Selection

The memory bank is resolved in this priority order:

1. URL path (highest priority): http://localhost:8888/mcp/my-bank/
2. X-Bank-Id header: --header "X-Bank-Id: my-bank"
3. Default: Uses HINDSIGHT_MCP_BANK_ID env var (default: "default")

Per-Bank Endpoints

Unlike traditional MCP servers where tools require explicit identifiers, Hindsight uses per-bank endpoints. The bank_id is part of the URL path, so tools don't need to specify which bank to use—it's implicit from the connection.

This design:

• Simplifies tool usage — no need to pass bank_id with every call
• Enforces isolation — each MCP connection is scoped to a single bank
• Enables multi-tenant setups — connect different users to different endpoints

Two Modes

The MCP server operates in two modes depending on the URL:

Mode	URL	Tools	bank_id
Single-bank	/mcp/{bank_id}/	Memory + mental model tools	Implicit from URL
Multi-bank	/mcp/	All tools including bank management	Explicit bank_id parameter on each tool

Single-bank mode (recommended) scopes all operations to the bank in the URL. Tools don't expose a bank_id parameter.

Multi-bank mode exposes all tools with an optional bank_id parameter, plus bank management tools (list_banks, create_bank).

---

Available Tools

retain

Store information to long-term memory.

Parameter	Type	Required	Description
content	string	Yes	The fact or memory to store
context	string	No	Category for the memory (default: general)
timestamp	string	No	ISO 8601 timestamp for when the event occurred

Example:

{
  "name": "retain",
  "arguments": {
    "content": "User prefers Python over JavaScript for backend development",
    "context": "programming_preferences"
  }
}

When to use:

• User shares personal facts, preferences, or interests
• Important events or milestones are mentioned
• Decisions, opinions, or goals are stated
• Work context or project details are discussed

---

recall

Search memories to provide personalized responses.

Parameter	Type	Required	Description
query	string	Yes	Natural language search query
max_tokens	integer	No	Maximum tokens to return (default: 4096)

Example:

{
  "name": "recall",
  "arguments": {
    "query": "What are the user's programming language preferences?"
  }
}

When to use:

• Start of conversation to recall relevant context
• Before making recommendations
• When user asks about something they may have mentioned before
• To provide continuity across conversations

---

reflect

Generate thoughtful analysis by synthesizing stored memories with the bank's personality.

Parameter	Type	Required	Description
query	string	Yes	The question or topic to reflect on
context	string	No	Optional context about why this reflection is needed
budget	string	No	Search budget: low, mid, or high (default: low)

Example:

{
  "name": "reflect",
  "arguments": {
    "query": "Based on my past decisions, what architectural style do I prefer?",
    "budget": "mid"
  }
}

When to use:

• When reasoned analysis is needed, not just fact retrieval
• Questions like "What should I do?" rather than "What did I say?"
• Synthesizing patterns across multiple memories

---

create_mental_model

Create a mental model — a living document that stays current with your memories. Mental models are pre-computed reflections that get automatically refreshed as new memories are stored.

Parameter	Type	Required	Description
name	string	Yes	Human-readable name for the mental model
source_query	string	Yes	The query used to generate and refresh the model
mental_model_id	string	No	Custom ID (alphanumeric lowercase with hyphens). Auto-generated if not provided
tags	list[string]	No	Tags for organizing and filtering models
max_tokens	integer	No	Maximum tokens for model content (default: 2048)

Example:

{
  "name": "create_mental_model",
  "arguments": {
    "name": "Team Directory",
    "source_query": "Who works here and what do they do?",
    "tags": ["team", "people"]
  }
}

Content generation runs asynchronously. The response includes an operation_id to track progress.

---

list_mental_models

List all mental models in a bank, optionally filtered by tags.

Parameter	Type	Required	Description
tags	list[string]	No	Filter models by tags

---

get_mental_model

Retrieve a specific mental model by ID, including its full content.

Parameter	Type	Required	Description
mental_model_id	string	Yes	The ID of the mental model to retrieve

---

update_mental_model

Update a mental model's metadata or settings.

Parameter	Type	Required	Description
mental_model_id	string	Yes	The ID of the mental model to update
name	string	No	New name
source_query	string	No	New source query
tags	list[string]	No	New tags
max_tokens	integer	No	New max tokens

---

delete_mental_model

Permanently delete a mental model.

Parameter	Type	Required	Description
mental_model_id	string	Yes	The ID of the mental model to delete

---

refresh_mental_model

Re-generate a mental model's content from the latest memories. Runs asynchronously.

Parameter	Type	Required	Description
mental_model_id	string	Yes	The ID of the mental model to refresh

---

list_banks (multi-bank mode only)

List all available memory banks.

---

create_bank (multi-bank mode only)

Create a new memory bank or retrieve an existing one.

Parameter	Type	Required	Description
bank_id	string	Yes	The ID for the new bank
name	string	No	Human-friendly name for the bank
mission	string	No	Mission describing who the agent is and what they're trying to accomplish

---

Integration with AI Assistants

The MCP server can be used with any MCP-compatible AI assistant. See the Authentication section above for Claude Code and Claude Desktop configuration examples.

Each user can have their own configuration pointing to their personal memory bank using either:

• A bank-specific URL path like /mcp/alice/ (recommended)
• The X-Bank-Id header