MCP DuckDB Knowledge Graph Memory Server

Instructions

Implementation Reference

• src/server.ts:123-128 (handler)

  Handler function for the delete_observations tool that calls the knowledge graph manager to perform the deletion and returns a success message.

  async ({ deletions }) => {
    await knowledgeGraphManager.deleteObservations(deletions);
    return {
      content: [{ type: "text", text: "Observations deleted successfully" }],
    };
  }

• src/server.ts:106-129 (registration)

  Registration of the delete_observations MCP tool including description, input schema, and handler reference.

  server.tool(
    "delete_observations",
    "Delete specific observations from entities in the knowledge graph",
    {
      deletions: z
        .array(
          z.object({
            entityName: z
              .string()
              .describe("The name of the entity containing the observations"),
            contents: z
              .array(z.string())
              .describe("An array of observations to delete"),
          })
        )
        .describe("An array of observation deletions"),
    },
    async ({ deletions }) => {
      await knowledgeGraphManager.deleteObservations(deletions);
      return {
        content: [{ type: "text", text: "Observations deleted successfully" }],
      };
    }
  );

• src/server.ts:109-122 (schema)

  Zod schema defining the input for delete_observations: array of objects with entityName and contents.

  {
    deletions: z
      .array(
        z.object({
          entityName: z
            .string()
            .describe("The name of the entity containing the observations"),
          contents: z
            .array(z.string())
            .describe("An array of observations to delete"),
        })
      )
      .describe("An array of observation deletions"),
  },

• src/manager.ts:463-495 (helper)

  Core implementation of observation deletion in KnowledgeGraphManager: performs SQL deletes in transaction and updates search index.

  async deleteObservations(deletions: Array<Observation>): Promise<void> {
    using conn = await this.getConn();
  
    try {
      // Begin transaction
      await conn.execute("BEGIN TRANSACTION");
  
      // Process each deletion
      for (const deletion of deletions) {
        // If there are observations to delete
        if (deletion.contents.length > 0) {
          for (const content of deletion.contents) {
            await conn.execute(
              "DELETE FROM observations WHERE entityName = ? AND content = ?",
              [deletion.entityName, content]
            );
          }
        }
      }
  
      // Commit transaction
      await conn.execute("COMMIT");
  
      // Update Fuse.js index
      const allEntities = await this.getAllEntities();
      this.fuse.setCollection(allEntities);
    } catch (error: unknown) {
      // Rollback in case of error
      await conn.execute("ROLLBACK");
      this.logger.error("Error deleting observations", extractError(error));
      throw error;
    }
  }

• src/types.ts:60-60 (schema)

  Type definition for the deleteObservations method in KnowledgeGraphManagerInterface.

  deleteObservations(deletions: Array<Observation>): Promise<void>;