read_memory_block

Retrieve full details of a specific memory block by its ID to access stored information in the Letta system.

Instructions

Get full details of a specific memory block by ID. Use list_memory_blocks to find block IDs. After reading, use update_memory_block to modify content.

Input Schema

TableJSON Schema

Name	Required	Description	Default
`block_id`	Yes	ID of the memory block to retrieve
`agent_id`	No	Optional agent ID for authorization

Implementation Reference

src/tools/memory/read-memory-block.js:4-36 (handler)

The main handler function that validates input arguments, fetches the memory block via API call to `/blocks/${block_id}`, formats the response as MCP content, and handles errors.

export async function handleReadMemoryBlock(server, args) {
    try {
        // Validate arguments
        if (!args?.block_id) {
            throw new Error('Missing required argument: block_id');
        }

        // Headers for API requests
        const headers = server.getApiHeaders();

        // If agent_id is provided, set the user_id header
        if (args.agent_id) {
            headers['user_id'] = args.agent_id;
        }

        // Get the memory block
        const response = await server.api.get(`/blocks/${args.block_id}`, {
            headers,
        });

        // Format the response
        return {
            content: [
                {
                    type: 'text',
                    text: JSON.stringify(response.data),
                },
            ],
        };
    } catch (error) {
        server.createErrorResponse(error);
    }
}

src/tools/memory/read-memory-block.js:41-59 (schema)

Tool definition including input schema for block_id (required) and optional agent_id.

export const readMemoryBlockToolDefinition = {
    name: 'read_memory_block',
    description:
        'Get full details of a specific memory block by ID. Use list_memory_blocks to find block IDs. After reading, use update_memory_block to modify content.',
    inputSchema: {
        type: 'object',
        properties: {
            block_id: {
                type: 'string',
                description: 'ID of the memory block to retrieve',
            },
            agent_id: {
                type: 'string',
                description: 'Optional agent ID for authorization',
            },
        },
        required: ['block_id'],
    },
};

src/tools/output-schemas.js:450-460 (schema)

Output schema defining the structure of the memory block response (id, name, label, value, metadata).

read_memory_block: {
    type: 'object',
    properties: {
        id: { type: 'string' },
        name: { type: 'string' },
        label: { type: 'string' },
        value: { type: 'string' },
        metadata: { type: 'object' },
    },
    required: ['id', 'name', 'label', 'value'],
},

src/tools/index.js:165-166 (registration)
Registration of the handler in the main tool call switch statement within registerToolHandlers.
```
case 'read_memory_block':
    return handleReadMemoryBlock(server, request.params.arguments);
```
src/tools/index.js:21-23 (registration)
Import of the handler and tool definition from the implementation file.
```
    handleReadMemoryBlock,
    readMemoryBlockToolDefinition,
} from './memory/read-memory-block.js';
```

src/tools/annotations.js:89-95 (helper)

Annotations providing metadata about the tool's behavior (read-only, auth required, low cost, fast execution).

read_memory_block: {
    title: 'Read Memory Block',
    readOnly: true,
    requiresAuth: true,
    costLevel: 'low',
    executionTime: 'fast',
},

Letta MCP Server