Vercel AI SDK / Cloud Platforms

Vercel AI SDK OpenAI-Compatible Provider Tool Calls Fail with Missing type object in JSON Schema

Fix tool call failures when using DeepSeek or other OpenAI-compatible providers with Vercel AI SDK Includes evidence for Vercel AI SDK troubleshooting demand.

Source-backed Last updated May 13, 2026 2 sources Needs local verification

Category: Cloud Platforms
Error signature: Invalid schema for function 'functionName': schema must be a JSON Schema of 'type: "object"', got 'type: null'
Quick fix: Check the build output, project root, and deployment platform configuration before redeploying.
Updated: May 13, 2026
Verification status: Source-backed
Evidence: 2 public source URLs

Before you change production

This page includes public source URLs in the imported troubleshooting record. Compare those references with your version and environment before applying changes.

Reproduce the smallest failing action and save non-secret logs before changing configuration.
Check versions for Vercel AI SDK, related SDKs, package managers, CI runners, and hosting providers.
Change one setting or dependency at a time, then rerun the same failing command or request.
Avoid destructive commands, credential rotation, billing changes, or security relaxations without a rollback plan.

What this error means

Invalid schema for function 'functionName': schema must be a JSON Schema of 'type: "object"', got 'type: null' is a Vercel AI SDK failure pattern reported for developers trying to fix tool call failures when using deepseek or other openai-compatible providers with vercel ai sdk. Based on the imported evidence, treat this as a tool-specific troubleshooting page rather than a generic API error.

Why this happens

Official Vercel AI SDK issue #7924 with 10+ comments. Root cause identified in provider-utils/schema.ts — asSchema() produces schemas without type: object. Multiple PRs (12283, 15163, 15249) attempted fixes. Affects all OpenAI-compatible providers that strictly validate JSON Schema.

Common causes

Developers using Vercel AI SDK with non-OpenAI providers (DeepSeek, local LLMs) encounter tool call failures because the SDK generates tool schemas without explicit type: object. This blocks production AI app deployments that rely on cost-effective alternative providers.
Official Vercel AI SDK issue #7924 with 10+ comments. Root cause identified in provider-utils/schema.ts — asSchema() produces schemas without type: object. Multiple PRs (12283, 15163, 15249) attempted fixes. Affects all OpenAI-compatible providers that strictly validate JSON Schema.

Quick fixes

Confirm the exact error signature matches Invalid schema for function 'functionName': schema must be a JSON Schema of 'type: "object"', got 'type: null'.
Check the Vercel AI SDK account, local tool state, and provider configuration involved in the failing workflow.
Check the build output, project root, and deployment platform configuration before redeploying.

Platform/tool-specific checks

Verify the command, editor, extension, or API client that produced the error.
Compare local settings with CI, deployment, or editor-level settings when the error appears in only one environment.
Avoid deleting credentials, local model data, or project settings until the failing scope is clear.

Step-by-step troubleshooting

Capture the exact error message and the command, editor action, or request that triggered it.
Check whether the failure is account/auth, quota/rate, model/provider, local runtime, or deployment configuration.
Review the source evidence below and compare it with your environment.
Apply one change at a time and rerun the smallest failing action.
Keep the working fix documented for the team or deployment environment.

How to prevent it

Keep provider/tool configuration documented.
Record non-secret diagnostics such as tool version, provider name, model name, and command path.
Add a lightweight check before CI or production workflows depend on the tool.

Diagnostic flow for this page

Match Invalid schema for function 'functionName': schema must be a JSON Schema of 'type: "object"', got 'type: null' exactly before applying the quick fix.
Compare the failing environment with Vercel AI SDK versions, account scope, provider settings, and deployment context.
Check the listed common causes in order, starting with the cause that best matches your logs.
Use the evidence status below to decide whether to confirm against public sources or official documentation.
Apply one reversible change, rerun the smallest failing action, and keep rollback notes.

FAQ

What does Invalid schema for function 'functionName': schema must be a JSON Schema of 'type: "object"', got 'type: null' mean in Vercel AI SDK?

Invalid schema for function 'functionName': schema must be a JSON Schema of 'type: "object"', got 'type: null' indicates the workflow described by "Vercel AI SDK OpenAI-Compatible Provider Tool Calls Fail with Missing type object in JSON Schema" failed in a Cloud Platforms context. Start by confirming the exact signature and the component that emitted it.

What should I check first for Invalid schema for function 'functionName': schema must be a JSON Schema of 'type: "object"', got 'type: null'?

Check whether this cause matches your environment: Developers using Vercel AI SDK with non-OpenAI providers (DeepSeek, local LLMs) encounter tool call failures because the SDK generates tool schemas without explicit type: object. This blocks production AI app deployments that rely on cost-effective alternative providers.

Is the Invalid schema for function 'functionName': schema must be a JSON Schema of 'type: "object"', got 'type: null' guidance source-backed?

The "Vercel AI SDK OpenAI-Compatible Provider Tool Calls Fail with Missing type object in JSON Schema" page is labeled source-backed. It has 2 public source URLs from github.com, so use that evidence status when deciding how much additional verification you need.

When should I avoid the quick fix for Invalid schema for function 'functionName': schema must be a JSON Schema of 'type: "object"', got 'type: null'?

For "Vercel AI SDK OpenAI-Compatible Provider Tool Calls Fail with Missing type object in JSON Schema", avoid applying "Check the build output, project root, and deployment platform configuration before redeploying." when the error text differs, the affected version or provider is different, or the change would touch credentials, billing, DNS, production deploy settings, or irreversible data.

What should I collect before debugging Invalid schema for function 'functionName': schema must be a JSON Schema of 'type: "object"', got 'type: null'?

For "Vercel AI SDK OpenAI-Compatible Provider Tool Calls Fail with Missing type object in JSON Schema", collect the failing Vercel AI SDK command or request, non-secret configuration, versions, timestamps, request IDs when available, and the smallest reproduction that still triggers the signature.