mcp-server-excel

Directly manipulates Excel cell values, formulas, and formatting through the native COM Interop API rather than file-based XML editing. Uses STA (Single-Threaded Apartment) threading model with ExcelBatch command queuing to ensure thread-safe, sequential execution of range operations. Changes are immediately visible in the running Excel instance without file corruption risk or round-trip serialization.

Generates and executes Power Query M-language scripts through the Excel COM API's QueryTable and DataModelConnection objects. Translates natural language intent into M-language transformations (filtering, grouping, pivoting, merging) and applies them to data connections. Supports both legacy QueryTable queries and modern Power Query data flows with automatic dependency resolution.

Manages workbook structure (sheet creation, deletion, reordering, protection) and sheet properties through the COM API's Worksheet and Workbook objects. Supports sheet visibility toggling, tab color assignment, and workbook-level settings (calculation mode, iteration limits). Handles sheet protection with password support.

Translates the 230+ Excel COM operations into MCP (Model Context Protocol) tool schemas that LLMs can understand and invoke. Each tool has a JSON schema describing parameters, return types, and constraints. The MCP server automatically routes natural language intents from Claude or other LLMs to the appropriate Excel command, handling parameter validation and error translation back to natural language.

Provides a command-line interface (excelcli) for executing Excel operations in batch mode. Uses Roslyn source generators to automatically generate C# code from CLI commands, enabling both imperative command execution and compiled code generation. Supports batch files with multiple commands, error handling, and result logging. Generated code can be compiled and reused without the CLI.

Manages multiple Excel instances and sessions through the ExcelMcpService daemon, which runs as a background Windows service. Each session maintains its own Excel COM context with isolated state. Supports session creation, switching, and cleanup with automatic resource management. Sessions persist across client disconnections, enabling long-running operations.

Implements OLE (Object Linking and Embedding) Message Filter to handle COM marshaling timeouts and transient failures. Automatically retries failed operations with exponential backoff and implements circuit breaker pattern for cascading failures. Translates low-level COM errors into actionable error messages with recovery suggestions.

Maintains contextual awareness of the current workbook, active sheet, and selected range, making this context available to AI agents without explicit specification. Automatically infers operation targets from context (e.g., 'format this range' applies to the currently selected range). Supports context switching and context stacking for nested operations.

Logs all Excel operations with timestamps, parameters, results, and execution time through a structured telemetry system. Supports multiple log sinks (file, cloud, database) and filtering by operation type or severity. Enables audit trails for compliance and debugging, with automatic PII redaction for sensitive data.

Provides a VS Code extension that integrates the MCP server, enabling developers to edit Excel files directly from VS Code with live preview and IntelliSense. Supports syntax highlighting for Excel formulas, range navigation, and quick actions for common operations. Extension communicates with the MCP server to execute operations and display results inline.

Constructs and manipulates Power Pivot data models using DAX (Data Analysis Expressions) formulas through the Excel COM API's DataModel object. Generates calculated columns, measures, and relationships between tables, then executes DAX queries to retrieve aggregated results. Supports both implicit (auto-detected) and explicit relationship definitions with cardinality validation.

Programmatically constructs PivotTables by configuring row/column/value fields, data sources, and aggregation functions through the Excel COM API's PivotTable object model. Supports both traditional PivotTables (from ranges) and modern PivotTables (from data models). Automatically handles field refresh, caching, and layout adjustments without manual UI interaction.

Creates and configures Excel charts (column, line, pie, scatter, etc.) by binding them to data ranges or PivotTables through the COM API's Chart object. Applies formatting (colors, legends, axis labels, data labels) and supports dynamic chart type switching. Charts automatically update when source data changes, enabling responsive dashboards.

Creates and manages named ranges and Excel tables (ListObjects) through the COM API, enabling formula references by semantic name rather than cell addresses. Supports dynamic range sizing (using OFFSET/INDIRECT) and automatic table expansion. Named ranges and tables are automatically available for use in formulas, PivotTables, and charts without manual reference updates.

Programmatically applies conditional formatting rules (color scales, data bars, icon sets, formula-based) to ranges through the COM API's FormatCondition object. Supports multiple rule types with priority-based evaluation and automatic color gradient generation. Rules are stored with the workbook and re-evaluate automatically when data changes.

Generates VBA (Visual Basic for Applications) code and injects it into Excel workbooks through the COM API's VBProject object. Supports macro creation, execution, and parameter passing. Handles macro security dialogs and enables/disables macros programmatically. Generated macros can call back into the MCP server for complex logic.

Manages external data connections (SQL Server, OData, CSV, etc.) through the COM API's Connections and QueryTable objects. Supports connection string updates, refresh scheduling, and error handling. Orchestrates refresh sequences for dependent queries and data models, with automatic retry logic and timeout management.

Programmatically creates slicers and filters for PivotTables and tables through the COM API's Slicer object. Supports multiple slicer types (date, text, numeric) with automatic value extraction from data sources. Slicers are connected to multiple PivotTables/tables, enabling synchronized filtering across the workbook.