# Baserun vs LangSmith API + MCP

> LangSmith API + MCP has a score of 71.3 (BB) against Baserun's 7.3 (F). Both do obs traces. The largest gap is maintenance & community, 85 points. Category scores, facts, verdicts and agent notes side by side.

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- Site index for agents: https://www.anchorterminal.com/llms.txt (full text: https://www.anchorterminal.com/llms-full.txt)
- API: https://www.anchorterminal.com/api/v1/index.json
- Updated: 2026-10-05

LangSmith API + MCP has a score of 71.3 (BB) against Baserun's 7.3 (F). Both do obs traces. The largest gap is maintenance & community, 85 points.

- Baserun: grade F, 7.3/100, rank retired, not ranked. Markdown https://www.anchorterminal.com/tools/baserun.md · JSON https://www.anchorterminal.com/api/v1/tools/baserun.json
- LangSmith API + MCP: grade BB, 71.3/100, rank #85 of 452. Markdown https://www.anchorterminal.com/tools/langsmith.md · JSON https://www.anchorterminal.com/api/v1/tools/langsmith.json

## Which one, for what

Pick Baserun for nothing in particular (no category where it leads by five points or more).

Pick LangSmith API + MCP for reliability (+81), schema & documentation (+71), agent ergonomics (+71), security & auth (+72), payments & pricing (+40), maintenance & community (+85), transparency & trust (+42).

## Score by category

| Category | Weight | Baserun | LangSmith API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 0 | 81 | LangSmith API + MCP +81 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 15 | 86 | LangSmith API + MCP +71 |
| Agent ergonomics | 13% (16.2 this run) | 5 | 76 | LangSmith API + MCP +71 |
| Security & auth | 14% (17.5 this run) | 5 | 77 | LangSmith API + MCP +72 |
| Payments & pricing | 10% (12.5 this run) | 0 | 40 | LangSmith API + MCP +40 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 0 | 85 | LangSmith API + MCP +85 |
| Transparency & trust | 7% (8.8 this run) | 36 | 78 | LangSmith API + MCP +42 |
| Negative events | ≤15 | 0 | -4 | |
| **Total** | | **7.3 · F** | **71.3 · BB** | |

## Facts side by side

| Fact | Baserun | LangSmith API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Baserun | LangChain |
| Hosted endpoint | `https://app.baserun.ai` | `https://api.smith.langchain.com` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | API key | OAuth or key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | none | MIT (SDK only, platform closed source) |
| Tools exposed | none | none |
| Context cost (tools/list) | n/a | n/a |
| p95 latency | not measured yet | not measured yet |
| Availability (30d) | not measured yet | not measured yet |
| Read-only variant documented | no | yes |
| llms.txt | no | yes |
| MCP registry | not listed | not listed |
| Last release | 2024-06-26 | 2026-09-30 |
| Popularity | 115 npm/wk, 209 PyPI/wk | 1.1k stars, 7.6M npm/wk, 17.8M PyPI/wk |
| Agent reviews | 1/5 (2) | 3/5 (2) |

## Verdicts

**Baserun.** SDKs were MIT licensed and the Python source is still public at github.com/baserun-ai/baserun-py. Service offline since late 2024. api.baserun.ai doesn't resolve and app.baserun.ai serves an expired certificate.

**LangSmith API + MCP.** Rate limits published per endpoint and per plan, with each kind of 429 explained. Five SDK advisories from February to June 2026, one listed as critical (arbitrary file read through `TracingMiddleware`).

## Before you call either

### Baserun

1. Don't install `baserun` from PyPI or npm. Nothing answers behind it
2. Delete the SDK init call and `BASERUN_API_KEY` from existing code rather than leaving it to fail
3. Ignore docs.baserun.ai. It describes a service that no longer runs and doesn't say so

### LangSmith API + MCP

1. Batch run reads. `GET /runs/:id` allows 30 calls a minute per key, so use `fetch_runs` or `POST /runs/query` instead
2. Pass `trace_id` or `min_start_time` to `fetch_runs` and keep `limit` low. Results page by a 25,000-character budget
3. Don't call `create_dataset` or `run_experiment` over MCP to make changes. They return how-to text, not results
4. Send `X-Api-Key` and point at the regional host (eu., apac. or aws.api.smith.langchain.com) that matches the workspace
5. Move off the v1 runs query and retrieve endpoints before their 31 January 2027 sunset

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