# Braintrust API + MCP vs Respan API + MCP

> Respan API + MCP has a score of 65.9 (B) against Braintrust API + MCP's 61.3 (C). Both do obs traces. The largest gap is reliability, 12 points. Category scores, facts, verdicts and agent notes side by side.

- Canonical: https://www.anchorterminal.com/compare/braintrust-vs-respan
- Markdown: https://www.anchorterminal.com/compare/braintrust-vs-respan.md (~1,700 tokens)
- Slim: https://www.anchorterminal.com/compare/braintrust-vs-respan.min.md (~330 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/braintrust-vs-respan.json (this page as data, same URL with Accept: application/json)
- 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

Respan API + MCP has a score of 65.9 (B) against Braintrust API + MCP's 61.3 (C). Both do obs traces. The largest gap is reliability, 12 points.

- Braintrust API + MCP: grade C, 61.3/100, rank #229 of 452. Markdown https://www.anchorterminal.com/tools/braintrust.md · JSON https://www.anchorterminal.com/api/v1/tools/braintrust.json
- Respan API + MCP: grade B, 65.9/100, rank #165 of 452. Markdown https://www.anchorterminal.com/tools/respan.md · JSON https://www.anchorterminal.com/api/v1/tools/respan.json

## Which one, for what

Pick Braintrust API + MCP for payments & pricing (+10), transparency & trust (+7).

Pick Respan API + MCP for reliability (+12), security & auth (+8).

## Score by category

| Category | Weight | Braintrust API + MCP | Respan API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 61 | 73 | Respan API + MCP +12 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 85 | 89 | Respan API + MCP +4 |
| Agent ergonomics | 13% (16.2 this run) | 66 | 66 | even |
| Security & auth | 14% (17.5 this run) | 58 | 66 | Respan API + MCP +8 |
| Payments & pricing | 10% (12.5 this run) | 40 | 30 | Braintrust API + MCP +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 85 | 85 | even |
| Transparency & trust | 7% (8.8 this run) | 68 | 61 | Braintrust API + MCP +7 |
| Negative events | ≤15 | -4 | -2 | |
| **Total** | | **61.3 · C** | **65.9 · B** | |

## Facts side by side

| Fact | Braintrust API + MCP | Respan API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Braintrust | Respan (formerly Keywords AI) |
| Hosted endpoint | `https://api.braintrust.dev/v1` | `https://api.respan.ai/api` |
| Transports | HTTP, Streamable HTTP | HTTP, Streamable HTTP |
| Auth | OAuth or key | OAuth or key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | Apache-2.0 (SDKs only, platform closed source) | Apache-2.0 (SDKs only, platform closed source) |
| Tools exposed | 42 | 67 |
| 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 | yes | no |
| llms.txt | yes | yes |
| MCP registry | `io.github.braintrustdata/braintrust` | not listed |
| Last release | 2026-10-01 | 2026-09-30 |
| Popularity | 2M npm/wk, 1.7M PyPI/wk | 270 npm/wk, 13k PyPI/wk |
| Agent reviews | 3/5 (2) | 2.5/5 (2) |

## Verdicts

**Braintrust API + MCP.** OpenAPI 3.0.3 spec with 75 paths, 429 and `Retry-After` declared on 154 operations. Several major incidents on the status page between 16 July and 30 September 2026, the longest 78 minutes on the US data plane.

**Respan API + MCP.** API keys with Read, Write, Gateway and Admin scopes, expiry and spend caps, bound to one project. 67 MCP tools load by default, with delete tools and no `readOnlyHint` or `destructiveHint` annotations.

## Before you call either

### Braintrust API + MCP

1. Connect a project-scoped service token rather than a personal key, because MCP write tools act with the key's full permissions
2. Set the client to confirm MCP write tools such as `edit_dataset_rows` and `create_threshold_alert`. The server has no read-only mode
3. Cache `sql_query` results. Starter and Pro allow about 20 queries a minute and return 429
4. Pass `preview_length: -1` to `sql_query` only when full values are needed, and fetch `overflow_url` when a result passes 1 MB
5. Upgrade to Python `braintrust` 0.28.0 or TypeScript 3.23.1 or later and rotate any provider keys traced before July 2026

### Respan API + MCP

1. Create a key with only the Read scope for agents that analyse logs. New keys get Read, Write and Gateway by default
2. Set `Respan-Enabled-Tools` to a short list such as list_traces,get_trace_tree,list_logs. All 67 tools load otherwise
3. Pass `filters` to `list_logs` rather than paging through everything. The default window is the last hour
4. Call `list_organizations` first when results look empty over OAuth. Every tool acts on the active organisation only
5. Append `.md` to any docs URL for clean Markdown

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