Moralis MCP Server

Instructions

Implementation Reference

• src/utils/execute-api-tool.ts:34-252 (handler)

  Generic handler that implements the execution logic for all dynamically generated API tools, including 'evm_gettokenholders'. It validates input using Zod, constructs the HTTP request to the Moralis API using the tool's path, method, params, etc., applies authentication, and formats the response.

  export async function executeApiTool(
    toolName: string,
    definition: McpToolDefinition,
    toolArgs: JsonObject,
    allSecuritySchemes: Record<string, any>,
    token?: string,
  ): Promise<CallToolResult> {
    try {
      // Validate arguments against the input schema
      let validatedArgs: JsonObject;
      try {
        const zodSchema = getZodSchemaFromJsonSchema(
          definition.inputSchema,
          toolName,
        );
        const argsToParse =
          typeof toolArgs === 'object' && toolArgs !== null ? toolArgs : {};
        validatedArgs = zodSchema.parse(argsToParse);
      } catch (error: unknown) {
        if (error instanceof ZodError) {
          const validationErrorMessage = `Invalid arguments for tool '${toolName}': ${error.errors.map((e) => `${e.path.join('.')} (${e.code}): ${e.message}`).join(', ')}`;
          return { content: [{ type: 'text', text: validationErrorMessage }] };
        } else {
          const errorMessage =
            error instanceof Error ? error.message : String(error);
          return {
            content: [
              {
                type: 'text',
                text: `Internal error during validation setup: ${errorMessage}`,
              },
            ],
          };
        }
      }
  
      // Prepare URL, query parameters, headers, and request body
      let urlPath = definition.pathTemplate;
      const queryParams: Record<string, any> = {};
      const headers: Record<string, string> = {
        Accept: 'application/json',
        'X-Moralis-Platform': 'MCP',
      };
      let requestBodyData: any = undefined;
  
      // Apply parameters to the URL path, query, or headers
      definition.executionParameters.forEach((param) => {
        const value = validatedArgs[param.name];
        if (typeof value !== 'undefined' && value !== null) {
          if (param.in === 'path') {
            urlPath = urlPath.replace(
              `{${param.name}}`,
              encodeURIComponent(String(value)),
            );
          } else if (param.in === 'query') {
            queryParams[param.name] = value;
          } else if (param.in === 'header') {
            headers[param.name.toLowerCase()] = String(value);
          }
        }
      });
  
      // Ensure all path parameters are resolved
      if (urlPath.includes('{')) {
        throw new Error(`Failed to resolve path parameters: ${urlPath}`);
      }
  
      // Construct the full URL
      const requestUrl = `${definition.baseUrl}${urlPath}`;
  
      // Handle request body if needed
      if (
        definition.requestBodyContentType &&
        typeof validatedArgs['requestBody'] !== 'undefined'
      ) {
        requestBodyData = validatedArgs['requestBody'];
        headers['content-type'] = definition.requestBodyContentType;
      }
  
      // Apply security requirements if available
      // Security requirements use OR between array items and AND within each object
      const appliedSecurity = definition.securityRequirements?.find((req) => {
        // Try each security requirement (combined with OR)
        return Object.entries(req).every(([schemeName, scopesArray]) => {
          const scheme = allSecuritySchemes[schemeName];
          if (!scheme) return false;
  
          // API Key security (header, query, cookie)
          if (scheme.type === 'apiKey') {
            return !!token || !!Config.MORALIS_API_KEY;
          }
  
          return false;
        });
      });
  
      // If we found matching security scheme(s), apply them
      if (appliedSecurity) {
        // Apply each security scheme from this requirement (combined with AND)
        for (const [schemeName, scopesArray] of Object.entries(appliedSecurity)) {
          const scheme = allSecuritySchemes[schemeName];
  
          // API Key security
          if (scheme?.type === 'apiKey') {
            const apiKey = token || Config.MORALIS_API_KEY;
            if (apiKey) {
              if (scheme.in === 'header') {
                headers[scheme.name.toLowerCase()] = apiKey;
                console.error(
                  `Applied API key '${schemeName}' in header '${scheme.name}'`,
                );
              }
            }
          }
        }
      }
      // Log warning if security is required but not available
      else if (definition.securityRequirements?.length > 0) {
        // First generate a more readable representation of the security requirements
        const securityRequirementsString = definition.securityRequirements
          .map((req) => {
            const parts = Object.entries(req)
              .map(([name, scopesArray]) => {
                const scopes = scopesArray as string[];
                if (scopes.length === 0) return name;
                return `${name} (scopes: ${scopes.join(', ')})`;
              })
              .join(' AND ');
            return `[${parts}]`;
          })
          .join(' OR ');
  
        console.warn(
          `Tool '${toolName}' requires security: ${securityRequirementsString}, but no suitable credentials found.`,
        );
      }
  
      // Prepare the axios request configuration
      const config: AxiosRequestConfig = {
        method: definition.method.toUpperCase(),
        url: requestUrl,
        params: queryParams,
        headers: headers,
        ...(requestBodyData !== undefined && { data: requestBodyData }),
      };
  
      // Log request info to stderr (doesn't affect MCP output)
      console.error(
        `Executing tool "${toolName}": ${config.method} ${config.url}`,
      );
  
      // Execute the request
      const response = await axios(config);
  
      // Process and format the response
      let responseText = '';
      const contentType = response.headers['content-type']?.toLowerCase() || '';
  
      // Handle JSON responses
      if (
        contentType.includes('application/json') &&
        typeof response.data === 'object' &&
        response.data !== null
      ) {
        try {
          responseText = JSON.stringify(response.data, null, 2);
        } catch (e) {
          responseText = '[Stringify Error]';
        }
      }
      // Handle string responses
      else if (typeof response.data === 'string') {
        responseText = response.data;
      }
      // Handle other response types
      else if (response.data !== undefined && response.data !== null) {
        responseText = String(response.data);
      }
      // Handle empty responses
      else {
        responseText = `(Status: ${response.status} - No body content)`;
      }
  
      // Return formatted response
      return {
        content: [
          {
            type: 'text',
            text: `API Response (Status: ${response.status}):\n${responseText}`,
          },
        ],
      };
    } catch (error: unknown) {
      // Handle errors during execution
      let errorMessage: string;
  
      // Format Axios errors specially
      if (axios.isAxiosError(error)) {
        errorMessage = formatApiError(error);
      }
      // Handle standard errors
      else if (error instanceof Error) {
        errorMessage = error.message;
      }
      // Handle unexpected error types
      else {
        errorMessage = `Unexpected error: ${String(error)}`;
      }
  
      // Log error to stderr
      console.error(
        `Error during execution of tool '${toolName}':`,
        errorMessage,
      );
  
      // Return error message to client
      return { content: [{ type: 'text', text: errorMessage }] };
    }
  }

• src/server.ts:26-44 (registration)

  Registers all tools from the OpenAPI spec by extracting tool definitions with the 'evm_' prefix from Moralis EVM API spec and building the toolDefinitionMap used for listTools and callTool.

  async function mapToolDefinitions(config: SchemaConfig) {
    const spec = (await getSpec(config.specUrl)) as OpenAPIV3DocumentX;
    const api = (await SwaggerParser.dereference(spec)) as OpenAPIV3DocumentX;
  
    const tools = extractToolsFromApi(api, config.prefix);
    const blacklist = Array.isArray(api['x-mcp-blacklist'])
      ? api['x-mcp-blacklist'].map((e) => `${config.prefix}${e.toLowerCase()}`)
      : [];
  
    const toolDefinitionMap: Record<string, McpToolDefinition> = {};
    for (const tool of tools) {
      if (blacklist.includes(tool.name)) continue;
      toolDefinitionMap[tool.name] = {
        ...tool,
        baseUrl: config.baseUrl,
      };
    }
    return toolDefinitionMap;
  }

• src/parser/extract-tools.ts:17-93 (schema)

  Extracts and generates MCP tool schemas (inputSchema) and definitions from the OpenAPI document. For EVM tools, prefix 'evm_' is added, creating tools like 'evm_gettokenholders' from matching operationIds/paths.

  export function extractToolsFromApi(
    api: OpenAPIV3DocumentX,
    prefix?: string
  ): McpToolDefinition[] {
    const tools: McpToolDefinition[] = [];
    const usedNames = new Set<string>();
    const globalSecurity = api.security || [];
  
    if (!api.paths) return tools;
  
    for (const [path, pathItem] of Object.entries(api.paths)) {
      if (!pathItem) continue;
  
      for (const method of Object.values(OpenAPIV3.HttpMethods)) {
        const operation = pathItem[method];
        if (!operation) continue;
  
        // Generate a unique name for the tool
        let baseName = operation.operationId || generateOperationId(method, path);
        if (!baseName) continue;
  
        // Sanitize the name to be MCP-compatible (only a-z, 0-9, _, -)
        baseName = baseName
          .replace(/\./g, '_')
          .replace(/[^a-z0-9_-]/gi, '_')
          .toLowerCase();
  
        let finalToolName = baseName;
        let counter = 1;
        while (usedNames.has(finalToolName)) {
          finalToolName = `${baseName}_${counter++}`;
        }
        usedNames.add(finalToolName);
  
        // Get or create a description
        const description =
          operation.description ||
          operation.summary ||
          `Executes ${method.toUpperCase()} ${path}`;
  
        const prompt = operation['x-mcp-prompt'];
  
        // Generate input schema and extract parameters
        const { inputSchema, parameters, requestBodyContentType } =
          generateInputSchemaAndDetails(operation);
  
        // Extract parameter details for execution
        const executionParameters = parameters.map((p) => ({
          name: p.name,
          in: p.in,
        }));
  
        // Determine security requirements
        const securityRequirements =
          operation.security === null
            ? globalSecurity
            : operation.security || globalSecurity;
  
        // Create the tool definition
        tools.push({
          name: prefix + finalToolName,
          description,
          inputSchema,
          method,
          pathTemplate: path,
          parameters,
          executionParameters,
          requestBodyContentType,
          securityRequirements,
          operationId: baseName,
          prompt,
        });
      }
    }
  
    return tools;
  }

• src/server.ts:96-120 (registration)

  MCP CallTool handler that looks up the tool definition by name (e.g., 'evm_gettokenholders') and dispatches to the executeApiTool handler.

  server.setRequestHandler(
    CallToolRequestSchema,
    async (request: CallToolRequest, c): Promise<CallToolResult> => {
      const { name: toolName, arguments: toolArgs } = request.params;
      const toolDefinition = toolDefinitionMap[toolName];
      if (!toolDefinition) {
        console.error(`Error: Unknown tool requested: ${toolName}`);
        return {
          content: [
            {
              type: 'text',
              text: `Error: Unknown tool requested: ${toolName}`,
            },
          ],
        };
      }
      return executeApiTool(
        toolName,
        toolDefinition,
        toolArgs ?? {},
        securitySchemes,
        c.authInfo?.token,
      );
    },
  );

• src/config.ts:15-22 (helper)

  Configuration for EVM tools, providing the 'evm_' prefix and URLs for the Moralis Deep Index API spec and base, from which 'evm_gettokenholders' is derived.

  evm:  {
    prefix: 'evm_',
    baseUrl:
      process.env.API_BASE_URL || 'https://deep-index.moralis.io/api/v2.2',
    specUrl:
      process.env.API_SPEC_URL ||
      'https://deep-index.moralis.io/api-docs-2.2/v2.2/swagger.json',
  },