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NovaAI-innovation

CSV MCP Server

read_csv

Extract data from CSV files by specifying a filename and optional row limit, returning structured content with metadata for analysis or processing.

Instructions

Read and return CSV file contents.

Args:
    filename: Name of the CSV file to read
    limit: Optional limit on number of rows to return

Returns:
    Dictionary with file contents and metadata

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
filenameYes
limitNo

Output Schema

TableJSON Schema
NameRequiredDescriptionDefault
resultYes

Implementation Reference

  • MCP tool handler for 'read_csv'. Decorated with @mcp.tool(), defines input parameters (filename, optional limit) and delegates to CSVManager.read_csv, handling exceptions.
    @mcp.tool()
    def read_csv(filename: str, limit: Optional[int] = None) -> Dict[str, Any]:
        """
        Read and return CSV file contents.
        
        Args:
            filename: Name of the CSV file to read
            limit: Optional limit on number of rows to return
        
        Returns:
            Dictionary with file contents and metadata
        """
        try:
            return csv_manager.read_csv(filename, limit)
        except Exception as e:
            return {"success": False, "error": str(e)}
  • Core implementation in CSVManager class: resolves file path, loads CSV with pandas.read_csv, applies row limit if specified, converts to dict records, returns structured response with metadata.
    def read_csv(self, filename: str, limit: Optional[int] = None) -> Dict[str, Any]:
        """Read CSV file contents."""
        filepath = self._get_file_path(filename)
        
        if not filepath.exists():
            raise FileNotFoundError(f"CSV file '{filename}' not found")
        
        try:
            df = pd.read_csv(filepath)
            
            # Apply limit if specified
            if limit and limit > 0:
                df = df.head(limit)
            
            return {
                "success": True,
                "filename": filename,
                "data": df.to_dict('records'),
                "columns": list(df.columns),
                "total_rows": len(df),
                "shape": df.shape
            }
        except Exception as e:
            logger.error(f"Failed to read CSV: {e}")
            raise
  • The @mcp.tool() decorator registers this function as the 'read_csv' tool in the FastMCP server.
    @mcp.tool()
    def read_csv(filename: str, limit: Optional[int] = None) -> Dict[str, Any]:
        """
        Read and return CSV file contents.
        
        Args:
            filename: Name of the CSV file to read
            limit: Optional limit on number of rows to return
        
        Returns:
            Dictionary with file contents and metadata
        """
        try:
            return csv_manager.read_csv(filename, limit)
        except Exception as e:
            return {"success": False, "error": str(e)}
Behavior2/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries the full burden of behavioral disclosure. While 'Read and return CSV file contents' implies a read-only operation, it doesn't disclose important behavioral traits: whether it reads from a specific directory/path, what happens if the file doesn't exist, whether there are file size limits, what authentication is needed, or how errors are handled. For a file I/O tool with zero annotation coverage, this is inadequate.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is perfectly structured and concise. It begins with a clear purpose statement, then provides organized parameter explanations in an 'Args:' section, and concludes with return information. Every sentence earns its place - no redundant information, no fluff, and the most important information (what the tool does) is front-loaded.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

Given the tool's moderate complexity (file I/O with 2 parameters), no annotations, but with an output schema present, the description is minimally adequate. The output schema existence means the description doesn't need to detail return values. However, for a file reading tool with no annotations, it should ideally mention basic behavioral expectations like error handling or file location assumptions to reach a higher completeness score.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters4/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

The description adds meaningful semantics beyond the 0% schema description coverage. It explains that 'filename' is the 'Name of the CSV file to read' and 'limit' is an 'Optional limit on number of rows to return' - clarifying the purpose of each parameter. Since schema coverage is 0% (no descriptions in schema properties), the description fully compensates by explaining both parameters' roles and the optional nature of 'limit'.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool's purpose with 'Read and return CSV file contents' - a specific verb (read/return) and resource (CSV file). It distinguishes from siblings like 'list_csv_files' (which lists files rather than reading contents) and 'validate_data' (which validates rather than reads). However, it doesn't explicitly differentiate from all 13 siblings, keeping it at 4 rather than 5.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines2/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description provides no guidance on when to use this tool versus alternatives. With 13 sibling tools including 'list_csv_files', 'get_info', 'get_path_info', and various data manipulation tools, there's no indication of when read_csv is appropriate versus other reading or information-gathering tools. The description only states what it does, not when to choose it.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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