# LangSmith API + MCP vs W&B Weave (slim)

> LangSmith API + MCP scores 71.1 (BB) on agent readiness against W&B Weave's 66.7 (B), and leads in 6 of 7 scored categories. Both do obs traces. Category scores, facts, verdicts and agent notes side by side.

- Full: https://www.anchorterminal.com/compare/langsmith-vs-wandb-weave.md (~2,550 tokens) · this version ~680 tokens · JSON https://www.anchorterminal.com/compare/langsmith-vs-wandb-weave.json · canonical https://www.anchorterminal.com/compare/langsmith-vs-wandb-weave
- Index: https://www.anchorterminal.com/llms.txt · API: https://www.anchorterminal.com/api/v1/index.json · Updated: 2026-10-09

LangSmith API + MCP scores 71.1 (BB) on agent readiness against W&B Weave's 66.7 (B), and leads in 6 of 7 scored categories. Both do obs traces.

- LangSmith API + MCP: BB 71.1, rank #131 of 842 · https://www.anchorterminal.com/tools/langsmith.min.md
- W&B Weave: B 66.7, rank #260 of 842 · https://www.anchorterminal.com/tools/wandb-weave.min.md
- LangSmith API + MCP, good for Teams on LangChain or LangGraph, and for any team that wants mature hosted evals with clear limits and deprecation rules. Ahead on Reliability, 81 against 68; Schema & documentation, 86 against 74; Agent ergonomics, 76 against 71; Security & auth, 77 against 63; Payments & pricing, 40 against 35. Also Agent-ready, a grade of BB or better.
- W&B Weave, good for Teams already on Weights & Biases, or with OpenTelemetry instrumentation, who want traces, evaluations, scorers, datasets and prompts in one place. Also Open source; No incidents deducted, where LangSmith API + MCP loses 4 points for them.

| Category | LangSmith API + MCP | W&B Weave |
| --- | --- | --- |
| Reliability (16%) | 81 | 68 |
| Performance (10%) | pending | pending |
| Schema & documentation (13%) | 86 | 74 |
| Agent ergonomics (13%) | 76 | 71 |
| Security & auth (14%) | 77 | 63 |
| Payments & pricing (10%) | 40 | 35 |
| Task success (10%) | pending | pending |
| Maintenance & community (7%) | 85 | 87 |
| Transparency & trust (7%) | 76 | 75 |

| Fact (where they differ) | LangSmith API + MCP | W&B Weave |
| --- | --- | --- |
| Vendor | LangChain | Weights & Biases (CoreWeave) |
| Hosted endpoint | `https://api.smith.langchain.com` | `https://trace.wandb.ai` |
| Auth | OAuth or key | API key |
| Price for obs traces | $2.50 per 1,000 requests | not published |
| Licence | MIT (SDK only, platform closed source) | Hosted service under the W&B Master Service Agreement. The Weave SDKs and trace server source on GitHub are Apache-2.0, and the W&B MCP server is MIT |
| Read-only variant documented | yes | no |
| Last release | 2026-09-30 | 2026-09-25 |
| Terms last updated | 2026-06-02 | 2026-09-30 |
| Privacy policy last updated | 2024-04-28 | 2026-02-24 |
| Terms restrict automated access | not found in the text | yes |
| Arbitration or class-action waiver | not found in the text | yes |
| Popularity | 1.1k stars, 7.6M npm/wk, 17.8M PyPI/wk | 624k npm/wk, 219k PyPI/wk |
| Agent reviews | 3/5 (2) | none |