Avoid attempting to serialize the "tool" during tool call execution

[TooTallNate]

Fixed serialization issue when executing tool calls in DurableAgent.

What changed?

Modified the executeTool function in durable-agent.ts to extract the execute method from the tool object before calling it, rather than invoking it directly on the tool object. This prevents JavaScript from binding this to the tool object, which contains non-serializable properties like inputSchema.

How to test?

Test tool execution in workflows where tools have complex properties that can't be serialized. Verify that tool calls complete successfully without serialization errors.

Why make this change?

When a tool's execute function is used as a workflow step (marked with 'use step'), the step system attempts to capture and serialize this. Since the tool object contains non-serializable properties, this was causing failures. By extracting the execute function before calling it, we avoid the serialization of the entire tool object.

[changeset-bot]

🦋 Changeset detected

Latest commit: 2e34af0

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
@workflow/ai	Patch
@workflow/docs-typecheck	Patch

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Click here if you're a maintainer who wants to add another changeset to this PR

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Project	Deployment	Review	Updated (UTC)
example-nextjs-workflow-turbopack	Ready	Preview, Comment	Jan 15, 2026 6:59pm
example-nextjs-workflow-webpack	Ready	Preview, Comment	Jan 15, 2026 6:59pm
example-workflow	Ready	Preview, Comment	Jan 15, 2026 6:59pm
workbench-astro-workflow	Ready	Preview, Comment	Jan 15, 2026 6:59pm
workbench-express-workflow	Ready	Preview, Comment	Jan 15, 2026 6:59pm
workbench-fastify-workflow	Ready	Preview, Comment	Jan 15, 2026 6:59pm
workbench-hono-workflow	Ready	Preview, Comment	Jan 15, 2026 6:59pm
workbench-nitro-workflow	Ready	Preview, Comment	Jan 15, 2026 6:59pm
workbench-nuxt-workflow	Ready	Preview, Comment	Jan 15, 2026 6:59pm
workbench-sveltekit-workflow	Ready	Preview, Comment	Jan 15, 2026 6:59pm
workbench-vite-workflow	Ready	Preview, Comment	Jan 15, 2026 6:59pm
workflow-docs	Ready	Preview, Comment	Jan 15, 2026 6:59pm

[github-actions]

🧪 E2E Test Results

❌ Some tests failed

Summary

	Passed	Failed	Skipped	Total
✅ ▲ Vercel Production	418	0	11	429
✅ 💻 Local Development	382	0	8	390
✅ 📦 Local Production	382	0	8	390
✅ 🐘 Local Postgres	382	0	8	390
✅ 🪟 Windows	39	0	0	39
❌ 🌍 Community Worlds	147	21	0	168
Total	1750	21	35	1806

❌ Failed Tests

🌍 Community Worlds (21 failed)

mongodb (1 failed):

• webhookWorkflow

redis (1 failed):

• webhookWorkflow

starter (18 failed):

• addTenWorkflow
• addTenWorkflow
• error handling error propagation workflow errors nested function calls preserve message and stack trace
• error handling error propagation workflow errors cross-file imports preserve message and stack trace
• error handling error propagation step errors basic step error preserves message and stack trace
• error handling error propagation step errors cross-file step error preserves message and function names in stack
• error handling retry behavior regular Error retries until success
• error handling retry behavior FatalError fails immediately without retries
• error handling catchability FatalError can be caught and detected with FatalError.is()
• hookCleanupTestWorkflow - hook token reuse after workflow completion
• stepFunctionPassingWorkflow - step function references can be passed as arguments (without closure vars)
• stepFunctionWithClosureWorkflow - step function with closure variables passed as argument
• spawnWorkflowFromStepWorkflow - spawning a child workflow using start() inside a step
• pathsAliasWorkflow - TypeScript path aliases resolve correctly
• Calculator.calculate - static workflow method using static step methods from another class
• AllInOneService.processNumber - static workflow method using sibling static step methods
• ChainableService.processWithThis - static step methods using this to reference the class
• thisSerializationWorkflow - step function invoked with .call() and .apply()

turso (1 failed):

• webhookWorkflow

Details by Category

✅ ▲ Vercel Production

App	Passed	Failed	Skipped
✅ astro	38	0	1
✅ example	38	0	1
✅ express	38	0	1
✅ fastify	38	0	1
✅ hono	38	0	1
✅ nextjs-turbopack	38	0	1
✅ nextjs-webpack	38	0	1
✅ nitro	38	0	1
✅ nuxt	38	0	1
✅ sveltekit	38	0	1
✅ vite	38	0	1

✅ 💻 Local Development

App	Passed	Failed	Skipped
✅ astro-stable	38	0	1
✅ express-stable	38	0	1
✅ fastify-stable	38	0	1
✅ hono-stable	38	0	1
✅ nextjs-turbopack-stable	39	0	0
✅ nextjs-webpack-stable	39	0	0
✅ nitro-stable	38	0	1
✅ nuxt-stable	38	0	1
✅ sveltekit-stable	38	0	1
✅ vite-stable	38	0	1

✅ 📦 Local Production

App	Passed	Failed	Skipped
✅ astro-stable	38	0	1
✅ express-stable	38	0	1
✅ fastify-stable	38	0	1
✅ hono-stable	38	0	1
✅ nextjs-turbopack-stable	39	0	0
✅ nextjs-webpack-stable	39	0	0
✅ nitro-stable	38	0	1
✅ nuxt-stable	38	0	1
✅ sveltekit-stable	38	0	1
✅ vite-stable	38	0	1

✅ 🐘 Local Postgres

App	Passed	Failed	Skipped
✅ astro-stable	38	0	1
✅ express-stable	38	0	1
✅ fastify-stable	38	0	1
✅ hono-stable	38	0	1
✅ nextjs-turbopack-stable	39	0	0
✅ nextjs-webpack-stable	39	0	0
✅ nitro-stable	38	0	1
✅ nuxt-stable	38	0	1
✅ sveltekit-stable	38	0	1
✅ vite-stable	38	0	1

✅ 🪟 Windows

App	Passed	Failed	Skipped
✅ nextjs-turbopack	39	0	0

❌ 🌍 Community Worlds

App	Passed	Failed	Skipped
✅ mongodb-dev	3	0	0
❌ mongodb	38	1	0
✅ redis-dev	3	0	0
❌ redis	38	1	0
✅ starter-dev	3	0	0
❌ starter	21	18	0
✅ turso-dev	3	0	0
❌ turso	38	1	0

---

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[TooTallNate]

• Avoid attempting to serialize the "tool" during tool call execution #790 👈 (View in Graphite)
• main

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[Copilot]

Pull request overview

This PR fixes a serialization error that occurs when executing tool calls in DurableAgent where the tool's execute function is marked with 'use step'. The workflow step system attempts to capture and serialize the this context, which fails when this is bound to the tool object containing non-serializable properties like inputSchema.

Changes:

• Modified executeTool function to extract the execute method before calling it, preventing this binding to the tool object
• Added changeset documenting the fix

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
packages/ai/src/agent/durable-agent.ts	Extracted execute function to avoid this binding during tool execution
.changeset/rude-suits-wonder.md	Added changeset for patch version bump

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