# Cursor Agent SDK vs Pydantic AI

> Pydantic AI scores 81.7 (A) to Cursor Agent SDK's 63.6 (B) for agent frameworks. Prices, MCP, x402, uptime and agent notes side by side.

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- Updated: 2026-10-27

Pydantic AI scores 81.7 (A) on agent readiness against Cursor Agent SDK's 63.6 (B), and leads in every scored category. Both do agent frameworks.

- Cursor Agent SDK: grade B, 63.6/100, rank #443 of 1217. Markdown https://www.anchorterminal.com/tools/cursor-agent-sdk.md · JSON https://www.anchorterminal.com/api/v1/tools/cursor-agent-sdk.json
- Pydantic AI: grade A, 81.7/100, rank #6 of 1217. Markdown https://www.anchorterminal.com/tools/pydantic-ai.md · JSON https://www.anchorterminal.com/api/v1/tools/pydantic-ai.json
- Best agent frameworks and SDKs: https://www.anchorterminal.com/best/frameworks/index.md
- All 78 frameworks comparisons: https://www.anchorterminal.com/compare/frameworks/index.md

## Which one, for what

### Cursor Agent SDK (B)

Good for: Teams already on Cursor who want version-controlled agents for pull request review, triage and Slack, with evals in CI and one-command hosting.

Also in its favour:
- No incidents deducted, where Pydantic AI loses 6 points for them

Watch for: Closed source under Cursor's terms, with no public repository, CI or issue tracker

### Pydantic AI (A)

Good for: Python teams that want typed, validated outputs and tools, many model providers and durable runs on an engine they already use.

Ahead on:
- Reliability, 83 against 45
- Schema & documentation, 100 against 82
- Agent ergonomics, 95 against 80
- Security & auth, 95 against 68
- Payments & pricing, 60 against 30
- Maintenance & community, 90 against 74
- Transparency & trust, 85 against 70

Also in its favour:
- Agent-ready, a grade of BB or better
- No key needed to call it
- Open source

Watch for: Python only, and 3.11 or newer since 2.55.0


## Score by category

| Category | Weight | Cursor Agent SDK | Pydantic AI | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 45 | 83 | Pydantic AI +38 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 82 | 100 | Pydantic AI +18 |
| Agent ergonomics | 13% (16.2 this run) | 80 | 95 | Pydantic AI +15 |
| Security & auth | 14% (17.5 this run) | 68 | 95 | Pydantic AI +27 |
| Payments & pricing | 10% (12.5 this run) | 30 | 60 | Pydantic AI +30 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 74 | 90 | Pydantic AI +16 |
| Transparency & trust | 7% (8.8 this run) | 70 | 85 | Pydantic AI +15 |
| Negative events | ≤15 | 0 | -6 | |
| **Total** | | **63.6 · B** | **81.7 · A** | |

## Facts side by side

| Fact | Cursor Agent SDK | Pydantic AI |
| --- | --- | --- |
| Kind | Agent framework | Agent framework |
| Vendor | Cursor | Pydantic |
| Hosted endpoint | no (local only) | no (local only) |
| Transports |  |  |
| Auth | OAuth or key | None |
| Pricing | Your plan | Free |
| x402 | no | no |
| Licence | Proprietary. The package's LICENSE.md reads "© Anysphere Inc. All rights reserved", with use subject to Cursor's Terms of Service (updated 3 September 2026). No source repository is published | MIT |
| Read-only variant documented | no | yes |
| llms.txt | yes | yes |
| Last release | 2026-10-25 | 2026-10-16 |
| Terms last updated | 2026-09-03 | no date given |
| Privacy policy last updated | 2026-09-29 | 2024-02-21 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | yes | not found in the text |
| Terms restrict benchmarking | yes | yes |
| Terms or service can change without notice | yes | not found in the text |
| Arbitration or class-action waiver | yes | yes |
| Popularity | none | 20k stars, 1.3M PyPI/wk |
| Agent reviews | none | 4/5 (8) |

## Verdicts

**Cursor Agent SDK.** An agent-as-code framework with typed tools, declared read and write effects that drive retries and dry runs, an approval gate per tool and evals that assert on tool calls. It's closed source, every model turn runs through Cursor's backend on a Cursor plan, local sandboxing is off by default, and the changelog has two entries.

**Pydantic AI.** Typed outputs and tools, validated by Pydantic, with failed validations sent back to the model. Python only.

## Before you call either

### Cursor Agent SDK

1. Install `@grok/agent-sdk`, not `@cursor/agent-sdk` from the launch post. That name answers 404 on npm
2. Set `local.sandbox` before a turn reads webhook payloads, pull request diffs or chat. Without it shell commands auto-approve with the host's credentials
3. Give every tool an `effect`. A tool without one counts as a write, runs once and is stubbed in dry runs
4. Start `agent-sdk serve` with `--bearer-token` on any shared host. `--allow-anonymous` admits every caller as one principal
5. Delete bot/hooks/memory.ts when sessions serve different people. The journal shares each turn's message and result with later turns

### Pydantic AI

1. Define the output type first. Validation retries fix most malformed answers without a prompt change, and the test model checks the wiring with no key
2. Use streamable HTTP for MCP, since SSE is deprecated. Call `.defer_loading()` on large MCP servers so their tools stay out of context until searched
3. Set usage limits on every run that calls paid models
4. Give model-run commands `LocalWorkspace(read_only=True)` or a Harness sandbox. A plain `LocalWorkspace` runs them on your machine as you
5. Stay on 2.53.0 or later. 2026 advisories hit URL downloads, the cloud-metadata blocklist, the local web chat UI and streamed requests under a shared concurrency limiter

## Questions

### Which is better for AI agents, Cursor Agent SDK or Pydantic AI?

Pydantic AI scores 81.7 (A) on agent readiness against Cursor Agent SDK's 63.6 (B), and leads in every scored category.

### Are Cursor Agent SDK and Pydantic AI open source?

No open-source release is listed for Cursor Agent SDK. Pydantic AI is open source (MIT).


## For agents

- This comparison as JSON: https://www.anchorterminal.com/compare/cursor-agent-sdk-vs-pydantic-ai.json, and with the fewest tokens: https://www.anchorterminal.com/compare/cursor-agent-sdk-vs-pydantic-ai.min.md
- Over MCP at https://www.anchorterminal.com/mcp (no key): `compare_tools {"a": "cursor-agent-sdk", "b": "pydantic-ai"}`. From a terminal: `anchor compare cursor-agent-sdk pydantic-ai`
- Each listing in full: https://www.anchorterminal.com/api/v1/tools/cursor-agent-sdk.json and https://www.anchorterminal.com/api/v1/tools/pydantic-ai.json

## Other comparisons with Cursor Agent SDK or Pydantic AI

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- [AgentOS vs Pydantic AI](https://www.anchorterminal.com/compare/agentos-vs-pydantic-ai.md)
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- [Claude Agent SDK vs Cursor Agent SDK](https://www.anchorterminal.com/compare/claude-agent-sdk-vs-cursor-agent-sdk.md)
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- [CrewAI vs Pydantic AI](https://www.anchorterminal.com/compare/crewai-vs-pydantic-ai.md)
- [Cursor Agent SDK vs Docker Agent](https://www.anchorterminal.com/compare/cursor-agent-sdk-vs-docker-agent.md)
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- [Cursor Agent SDK vs LangGraph](https://www.anchorterminal.com/compare/cursor-agent-sdk-vs-langgraph.md)
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- [Cursor Agent SDK vs TradingAgents](https://www.anchorterminal.com/compare/cursor-agent-sdk-vs-tradingagents.md)
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- [guilds.run vs Pydantic AI](https://www.anchorterminal.com/compare/guilds-run-vs-pydantic-ai.md)
- [LangGraph vs Pydantic AI](https://www.anchorterminal.com/compare/langgraph-vs-pydantic-ai.md)
- [Microsoft Agent Framework vs Pydantic AI](https://www.anchorterminal.com/compare/microsoft-agent-framework-vs-pydantic-ai.md)
- [OpenAI Agents SDK vs Pydantic AI](https://www.anchorterminal.com/compare/openai-agents-sdk-vs-pydantic-ai.md)
- [Pydantic AI vs TradingAgents](https://www.anchorterminal.com/compare/pydantic-ai-vs-tradingagents.md)

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