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MoralisWeb3

Moralis MCP Server

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by MoralisWeb3

evm_getentitiesbycategory

Fetch blockchain entities by category to retrieve names, logos, descriptions, addresses, and external links for analysis.

Instructions

Fetch entities belonging to a specific category. Each entity returns name, logo, description, external links, total addresses and more.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
categoryIdYesThe category Id
limitNoThe desired page size of the result.

Implementation Reference

  • The core handler function that executes the 'evm_getentitiesbycategory' tool (and all others) by validating inputs, constructing the API request to the Moralis EVM endpoint, applying authentication, and returning the formatted 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:66-72 (registration)
    Registers all tools, including 'evm_getentitiesbycategory', by building toolDefinitionMap from EVM OpenAPI spec using prefix 'evm_' and extractToolsFromApi.
    let toolDefinitionMap: Record<string, McpToolDefinition> = {};
    for (const config of configArray)
      toolDefinitionMap = {
        ...toolDefinitionMap,
        ...(await mapToolDefinitions(config)),
      };
  • Extracts tool definitions from Moralis EVM OpenAPI spec, generating schema, name with 'evm_' prefix, description, parameters for 'getentitiesbycategory' operation.
    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:26-44 (registration)
    Maps OpenAPI spec from EVM_CONFIG.specUrl to tool definitions, applying 'evm_' prefix and filtering blacklist, populating toolDefinitionMap used for registration.
    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;
    }
  • EVM configuration defining 'evm_' prefix, baseUrl, and specUrl for the Moralis Deep Index API from which 'evm_getentitiesbycategory' is extracted.
    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 full burden. It mentions what data is returned (name, logo, description, etc.), which is useful, but lacks critical behavioral details: whether this is a read-only operation, if it requires authentication, rate limits, pagination behavior (limit parameter suggests pagination but no details), error conditions, or what 'more' includes. For a fetch tool with no annotation coverage, this is a significant gap.

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

Conciseness4/5

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

The description is a single, efficient sentence that front-loads the core purpose ('Fetch entities belonging to a specific category') and adds useful detail about return fields. It avoids redundancy and waste, though it could be slightly more structured (e.g., separating purpose from output details).

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 no annotations, no output schema, and a fetch operation with potential complexity (pagination, data richness), the description is incomplete. It lists return fields but doesn't cover behavioral aspects like safety, performance, or error handling. For a tool that returns 'more' data without an output schema, this leaves too much undefined.

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%, so the schema already documents both parameters (categoryId and limit). The description adds no additional parameter semantics beyond what's in the schema—it doesn't explain categoryId format, source, or valid values, or how limit interacts with pagination. Baseline 3 is appropriate when schema does the heavy lifting.

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: 'Fetch entities belonging to a specific category' (verb+resource). It distinguishes from siblings like 'evm_getentity' (single entity) and 'evm_searchentities' (search-based), but doesn't explicitly contrast with 'evm_getentitycategories' (which likely lists categories rather than entities within them). The description is specific but could be more precise about sibling differentiation.

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 categoryId from another tool), exclusions, or comparisons to siblings like 'evm_searchentities' for broader searches. Usage is implied only by the tool name and description, with no explicit context.

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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