fix(api): bound agent tool inputs

Author: TheodoreSpeaks

apps/docs/openapi-v2-workflows.json

@@ -6197,6 +6197,7 @@
         "description": "One semantic edit against a workflow graph."
       },
       "AgentToolInput": {
+        "maxItems": 100,
         "type": "array",
         "items": {
           "$ref": "#/components/schemas/AgentTool"
@@ -6315,6 +6316,7 @@
                       "name": {
                         "type": "string",
                         "minLength": 1,
+                        "maxLength": 64,
                         "description": "Function name presented to the model."
                       },
                       "description": {
@@ -6387,11 +6389,13 @@
                   "serverId": {
                     "type": "string",
                     "minLength": 1,
+                    "maxLength": 128,
                     "description": "MCP server id returned by `GET /api/v2/mcp-servers`."
                   },
                   "toolName": {
                     "type": "string",
                     "minLength": 1,
+                    "maxLength": 256,
                     "description": "Tool name returned by the MCP server’s tools endpoint."
                   }
                 },

apps/sim/lib/api/contracts/v2/__tests__/workflow-agent-tools.test.ts

@@ -2,10 +2,13 @@
  * @vitest-environment node
  */
 import { describe, expect, it } from 'vitest'
+import { MAX_ID_LENGTH } from '@/lib/api/contracts/primitives'
 import {
+  MAX_AGENT_TOOLS_PER_BLOCK,
   v2AgentToolInputSchema,
   v2ApplyWorkflowOperationsBodySchema,
 } from '@/lib/api/contracts/v2/workflows'
+import { MAX_MCP_TOOL_NAME_BYTES } from '@/lib/mcp/constants'
 
 describe('v2AgentToolInputSchema', () => {
   it('accepts catalog integration, custom-tool reference, and MCP tool shapes', () => {
@@ -57,6 +60,57 @@ describe('v2AgentToolInputSchema', () => {
   ])('rejects a malformed reserved tool shape', (tools) => {
     expect(v2AgentToolInputSchema.safeParse(tools).success).toBe(false)
   })
+
+  it('rejects a tool list above the workflow-operation ceiling', () => {
+    const tools = Array.from({ length: MAX_AGENT_TOOLS_PER_BLOCK + 1 }, (_, index) => ({
+      type: `integration-${index}`,
+    }))
+
+    expect(v2AgentToolInputSchema.safeParse(tools).success).toBe(false)
+  })
+
+  it.each([
+    [
+      'inline function name',
+      {
+        type: 'custom-tool',
+        schema: {
+          type: 'function',
+          function: { name: 'a'.repeat(65), parameters: { type: 'object' } },
+        },
+        code: 'return null',
+      },
+    ],
+    [
+      'MCP server id',
+      {
+        type: 'mcp',
+        params: { serverId: 'a'.repeat(MAX_ID_LENGTH + 1), toolName: 'search_docs' },
+      },
+    ],
+    [
+      'MCP tool name',
+      {
+        type: 'mcp',
+        params: {
+          serverId: 'mcp_123',
+          toolName: 'a'.repeat(MAX_MCP_TOOL_NAME_BYTES + 1),
+        },
+      },
+    ],
+    [
+      'MCP multibyte tool name',
+      {
+        type: 'mcp',
+        params: {
+          serverId: 'mcp_123',
+          toolName: '💡'.repeat(Math.floor(MAX_MCP_TOOL_NAME_BYTES / 4) + 1),
+        },
+      },
+    ],
+  ])('rejects an overlong %s', (_label, tool) => {
+    expect(v2AgentToolInputSchema.safeParse([tool]).success).toBe(false)
+  })
 })
 
 describe('workflow operation Agent tools contract', () => {

apps/sim/lib/api/contracts/v2/workflows.ts

@@ -17,6 +17,7 @@ import {
 } from '@/lib/api/contracts/deployments'
 import {
   booleanQueryFlagSchema,
+  MAX_ID_LENGTH,
   missingFieldError,
   noInputSchema,
   runIdSchema,
@@ -58,6 +59,7 @@ import {
 import { MAX_WORKFLOW_EXECUTION_TIMEOUT_SECONDS } from '@/lib/billing/execution-timeout-defaults'
 import { MAX_INLINE_MATERIALIZATION_BYTES } from '@/lib/execution/payloads/limits'
 import { PERSISTED_WORKFLOW_EXECUTION_STATUSES } from '@/lib/logs/types'
+import { MAX_MCP_TOOL_NAME_BYTES } from '@/lib/mcp/constants'
 import { WORKFLOW_SKIPPED_ITEM_TYPES } from '@/lib/workflows/editing/types'
 
 export const V2_WORKFLOW_RUN_ID_HEADER = 'X-Run-Id'
@@ -2053,6 +2055,8 @@ export const MAX_WORKFLOW_GRAPH_BLOCKS = 2000
 export const MAX_WORKFLOW_GRAPH_EDGES = 10_000
 /** Ceiling on one `POST /operations` batch. */
 export const MAX_WORKFLOW_EDIT_OPERATIONS = 200
+/** Ceiling on the complete tool list assigned to one Agent block. */
+export const MAX_AGENT_TOOLS_PER_BLOCK = 100
 /** Ceiling on one `PATCH /variables` batch; mirrors the application use case's own cap. */
 export const MAX_WORKFLOW_VARIABLE_OPERATIONS = 100
 /** Ceiling on one bulk move; mirrors the application use case's own cap. */
@@ -2727,6 +2731,7 @@ const v2AgentInlineCustomToolSchema = z
               .string()
               .trim()
               .min(1, 'Inline custom tool function name cannot be empty')
+              .max(64, 'Inline custom tool function name must be at most 64 characters')
               .describe('Function name presented to the model.'),
             description: z.string().optional().describe('What the inline custom tool does.'),
             parameters: z
@@ -2779,11 +2784,21 @@ export const v2AgentMcpToolSchema = z
               .string()
               .trim()
               .min(1, 'Agent MCP serverId cannot be empty')
+              .max(MAX_ID_LENGTH, `Agent MCP serverId must be at most ${MAX_ID_LENGTH} characters`)
               .describe('MCP server id returned by `GET /api/v2/mcp-servers`.'),
             toolName: z
               .string()
               .trim()
               .min(1, 'Agent MCP toolName cannot be empty')
+              .max(
+                MAX_MCP_TOOL_NAME_BYTES,
+                `Agent MCP toolName must be at most ${MAX_MCP_TOOL_NAME_BYTES} characters`
+              )
+              .refine(
+                (toolName) =>
+                  new TextEncoder().encode(toolName).byteLength <= MAX_MCP_TOOL_NAME_BYTES,
+                `Agent MCP toolName must be at most ${MAX_MCP_TOOL_NAME_BYTES} bytes`
+              )
               .describe('Tool name returned by the MCP server’s tools endpoint.'),
           })
           .catchall(z.unknown().describe('One parameter fixed by the workflow author.')),
@@ -2824,6 +2839,7 @@ export type V2AgentTool = z.input<typeof v2AgentToolSchema>
 /** The stored value of an Agent block's `tools` input. */
 export const v2AgentToolInputSchema = z
   .array(v2AgentToolSchema)
+  .max(MAX_AGENT_TOOLS_PER_BLOCK, `Agent tools cannot exceed ${MAX_AGENT_TOOLS_PER_BLOCK} entries`)
   .describe(
     'Tools the Agent may call. Integration `type` and `operation` values come from `GET /api/v2/blocks/{blockId}`; custom and MCP identifiers come from their workspace catalog endpoints.'
   )

scripts/openapi/documents.test.ts

@@ -1,6 +1,7 @@
 import { readFileSync } from 'node:fs'
 import path from 'node:path'
 import { describe, expect, it } from 'vitest'
+import { MAX_ID_LENGTH } from '../../apps/sim/lib/api/contracts/primitives'
 import { billingOpenApiDocument } from '../../apps/sim/lib/api/contracts/v2/openapi/billing'
 import { filesAuditOpenApiDocument } from '../../apps/sim/lib/api/contracts/v2/openapi/files-audit'
 import { knowledgeOpenApiDocument } from '../../apps/sim/lib/api/contracts/v2/openapi/knowledge'
@@ -14,6 +15,8 @@ import {
 } from '../../apps/sim/lib/api/contracts/v2/openapi/shared'
 import { tablesOpenApiDocument } from '../../apps/sim/lib/api/contracts/v2/openapi/tables'
 import { workflowsOpenApiDocument } from '../../apps/sim/lib/api/contracts/v2/openapi/workflows'
+import { MAX_AGENT_TOOLS_PER_BLOCK } from '../../apps/sim/lib/api/contracts/v2/workflows'
+import { MAX_MCP_TOOL_NAME_BYTES } from '../../apps/sim/lib/mcp/constants'
 import { generateOpenApiDocument, serializeOpenApiDocument } from './generator'
 
 type JsonObject = Record<string, unknown>
@@ -296,11 +299,18 @@ describe('generated OpenAPI documents', () => {
   it('publishes Agent tools as named integration, custom, and MCP schemas', () => {
     const workflowsSpec = generateOpenApiDocument(workflowsOpenApiDocument)
     const schemas = (workflowsSpec.components as JsonObject).schemas as JsonObject
+    const agentToolInput = schemas.AgentToolInput as JsonObject
     const agentTool = schemas.AgentTool as JsonObject
     const agentToolVariants = agentTool.oneOf as JsonObject[]
     const integrationTool = schemas.AgentIntegrationTool as JsonObject
     const integrationProperties = integrationTool.properties as JsonObject
     const customTool = schemas.AgentCustomTool as JsonObject
+    const customToolVariants = customTool.anyOf as JsonObject[]
+    const inlineCustomToolProperties = customToolVariants[1].properties as JsonObject
+    const inlineCustomToolSchema = inlineCustomToolProperties.schema as JsonObject
+    const inlineCustomToolSchemaProperties = inlineCustomToolSchema.properties as JsonObject
+    const inlineFunction = inlineCustomToolSchemaProperties.function as JsonObject
+    const inlineFunctionProperties = inlineFunction.properties as JsonObject
     const mcpTool = schemas.AgentMcpTool as JsonObject
     const mcpProperties = mcpTool.properties as JsonObject
     const mcpParams = mcpProperties.params as JsonObject
@@ -312,6 +322,9 @@ describe('generated OpenAPI documents', () => {
       { $ref: '#/components/schemas/AgentCustomTool' },
       { $ref: '#/components/schemas/AgentMcpTool' },
     ])
+    expect(agentToolInput).toEqual(
+      expect.objectContaining({ type: 'array', maxItems: MAX_AGENT_TOOLS_PER_BLOCK })
+    )
     expect(integrationProperties).toEqual(
       expect.objectContaining({
         type: expect.objectContaining({ type: 'string', pattern: expect.any(String) }),
@@ -321,11 +334,17 @@ describe('generated OpenAPI documents', () => {
       })
     )
     expect(customTool).toHaveProperty('anyOf')
+    expect(inlineFunctionProperties.name).toEqual(
+      expect.objectContaining({ type: 'string', maxLength: 64 })
+    )
     expect((mcpProperties.type as JsonObject).const).toBe('mcp')
     expect(mcpParamProperties).toEqual(
       expect.objectContaining({
-        serverId: expect.objectContaining({ type: 'string' }),
-        toolName: expect.objectContaining({ type: 'string' }),
+        serverId: expect.objectContaining({ type: 'string', maxLength: MAX_ID_LENGTH }),
+        toolName: expect.objectContaining({
+          type: 'string',
+          maxLength: MAX_MCP_TOOL_NAME_BYTES,
+        }),
       })
     )
     expect(JSON.stringify(schemas.WorkflowEditOperation)).toContain(