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MoralisWeb3

Moralis MCP Server

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by MoralisWeb3

evm_getblock

Retrieve detailed blockchain block contents using block number or hash, including optional internal transactions, across multiple supported chains.

Instructions

Get the contents of a block given the block hash.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
chainNoThe chain to queryeth
block_number_or_hashYesThe block number or block hash
includeNoIf the result should contain the internal transactions.

Implementation Reference

  • Generic execution handler for all API tools including 'evm_getblock'. Validates input using Zod from JSON schema, constructs HTTP request using tool definition (path, method, params, headers, auth), sends via axios to Moralis EVM API, and returns formatted response or error.
    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:97-120 (registration)
    MCP server registration of the CallToolRequestSchema handler. For 'evm_getblock', it retrieves the tool definition from the map (populated from EVM OpenAPI spec) and invokes the generic executeApiTool handler.
      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/server.ts:66-72 (registration)
    Populates toolDefinitionMap with tools extracted from OpenAPI specs, including 'evm_getblock' from the EVM config/spec with 'evm_' prefix.
    let toolDefinitionMap: Record<string, McpToolDefinition> = {};
    for (const config of configArray)
      toolDefinitionMap = {
        ...toolDefinitionMap,
        ...(await mapToolDefinitions(config)),
      };
  • Parses OpenAPI document to extract tool definitions for MCP, including schema/inputSchema for 'evm_getblock' based on the corresponding operationId in the Moralis EVM spec.
    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;
    }
  • EVM configuration defining the prefix 'evm_' (so getblock becomes evm_getblock), baseUrl for API calls, and specUrl for OpenAPI document used to extract tools/schemas.
    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',
    },
Behavior2/5

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

No annotations are provided, so the description carries the full burden of behavioral disclosure. It states the tool retrieves block contents but lacks details on permissions, rate limits, error handling, or response format. For a read operation in a blockchain context, this is a significant gap, as it doesn't explain what 'contents' includes (e.g., transactions, timestamps) or any constraints, making it minimally transparent.

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 a single, efficient sentence: 'Get the contents of a block given the block hash.' It is front-loaded with the core action and input, with zero wasted words. This makes it highly concise and well-structured for quick understanding, earning a top score.

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

Completeness2/5

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

Given the tool's complexity (blockchain data retrieval), lack of annotations, and no output schema, the description is incomplete. It doesn't explain the return format (e.g., JSON structure), error cases, or behavioral traits like rate limits. While the schema covers inputs well, the overall context for safe and effective use is insufficient, especially for a tool with potential nuances in blockchain queries.

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

Parameters3/5

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

Schema description coverage is 100%, meaning the schema already documents all parameters ('chain', 'block_number_or_hash', 'include') with descriptions and enums. The description adds no additional meaning beyond implying the use of a block hash, which is partially covered in the schema. With high schema coverage, the baseline score of 3 is appropriate, as the description doesn't compensate but doesn't detract either.

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: 'Get the contents of a block given the block hash.' This specifies the verb ('Get'), resource ('contents of a block'), and key input ('block hash'). It distinguishes from siblings like 'evm_getlatestblocknumber' (which gets only the number) and 'evm_gettransactionverbose' (which focuses on transactions). However, it doesn't explicitly differentiate from all siblings, such as those fetching token or NFT data, though the focus on blocks is inherently distinct.

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. It doesn't mention prerequisites (e.g., needing a valid block identifier), exclusions (e.g., not for real-time data), or direct alternatives among siblings. For example, it doesn't clarify if 'evm_getlatestblocknumber' should be used first to obtain a block number, leaving usage context implied at best.

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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