mcp-memory-libsql

Instructions

Implementation Reference

• src/index.ts:283-315 (handler)

  The handler function that implements the core logic of the 'delete_relation' MCP tool. It calls the database delete_relation method and formats the success or error response.

  async ({ source, target, type }) => {
  	try {
  		await db.delete_relation(source, target, type);
  		return {
  			content: [
  				{
  					type: 'text' as const,
  					text: `Successfully deleted relation: ${source} -> ${target} (${type})`,
  				},
  			],
  		};
  	} catch (error) {
  		return {
  			content: [
  				{
  					type: 'text' as const,
  					text: JSON.stringify(
  						{
  							error: 'internal_error',
  							message:
  								error instanceof Error
  									? error.message
  									: 'Unknown error',
  						},
  						null,
  						2,
  					),
  				},
  			],
  			isError: true,
  		};
  	}
  },

• src/index.ts:52-56 (schema)

  Valibot schema defining the input parameters for the delete_relation tool: source, target, and type as strings.

  const DeleteRelationSchema = v.object({
  	source: v.string(),
  	target: v.string(),
  	type: v.string(),
  });

• src/index.ts:277-282 (registration)

  Registration of the 'delete_relation' tool on the MCP server, specifying name, description, and schema.

  server.tool<typeof DeleteRelationSchema>(
  	{
  		name: 'delete_relation',
  		description: 'Delete a specific relation between entities',
  		schema: DeleteRelationSchema,
  	},

• src/db/client.ts:305-328 (helper)

  Database helper method that performs the actual SQL DELETE operation for a specific relation and handles errors.

  async delete_relation(
  	source: string,
  	target: string,
  	type: string,
  ): Promise<void> {
  	try {
  		const result = await this.client.execute({
  			sql: 'DELETE FROM relations WHERE source = ? AND target = ? AND relation_type = ?',
  			args: [source, target, type],
  		});
  
  		if (result.rowsAffected === 0) {
  			throw new Error(
  				`Relation not found: ${source} -> ${target} (${type})`,
  			);
  		}
  	} catch (error) {
  		throw new Error(
  			`Failed to delete relation: ${
  				error instanceof Error ? error.message : String(error)
  			}`,
  		);
  	}
  }