# Prefactor vs Respan API + MCP

> Prefactor and Respan API + MCP score within a point of each other on agent readiness, 65.6 (B) and 65.5 (B). Respan API + MCP leads on schema & documentation, security & auth and transparency & trust. Both do obs traces. Category scores, facts, verdicts and agent notes side by…

- Canonical: https://www.anchorterminal.com/compare/prefactor-vs-respan
- Markdown: https://www.anchorterminal.com/compare/prefactor-vs-respan.md (~2,300 tokens)
- Slim: https://www.anchorterminal.com/compare/prefactor-vs-respan.min.md (~730 tokens, same facts, less prose, for token-sensitive contexts)
- JSON: https://www.anchorterminal.com/compare/prefactor-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: 2026-10-08

Prefactor and Respan API + MCP score within a point of each other on agent readiness, 65.6 (B) and 65.5 (B). Respan API + MCP leads on schema & documentation, security & auth and transparency & trust. Both do obs traces.

- Prefactor: grade B, 65.6/100, rank #253 of 722. Markdown https://www.anchorterminal.com/tools/prefactor.md · JSON https://www.anchorterminal.com/api/v1/tools/prefactor.json
- Respan API + MCP: grade B, 65.5/100, rank #257 of 722. Markdown https://www.anchorterminal.com/tools/respan.md · JSON https://www.anchorterminal.com/api/v1/tools/respan.json

## Which one, for what

### Prefactor (B)

Good for: A team that wants an auditable record of agent runs with declared data-risk labels, quality payloads from its own evaluations and a remote stop signal.

Ahead on:
- Reliability, 78 against 73
- Agent ergonomics, 88 against 66
- Payments & pricing, 40 against 30

Also in its favour:
- Free to start without a card

Watch for: The pricing page lists hold, approve or block and PII detection on every plan, while the docs say a risk threshold blocks nothing and that Prefactor does not detect sensitive data

### Respan API + MCP (B)

Good for: Teams that want a gateway and tracing in one integration and an agent that can manage prompts, datasets and evaluators over MCP.

Ahead on:
- Schema & documentation, 89 against 80
- Security & auth, 66 against 56
- Transparency & trust, 57 against 42

Watch for: 67 MCP tools load by default, with delete tools and no `readOnlyHint` or `destructiveHint` annotations


## Score by category

| Category | Weight | Prefactor | Respan API + MCP | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 78 | 73 | Prefactor +5 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 80 | 89 | Respan API + MCP +9 |
| Agent ergonomics | 13% (16.2 this run) | 88 | 66 | Prefactor +22 |
| Security & auth | 14% (17.5 this run) | 56 | 66 | Respan API + MCP +10 |
| Payments & pricing | 10% (12.5 this run) | 40 | 30 | Prefactor +10 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 82 | 85 | Respan API + MCP +3 |
| Transparency & trust | 7% (8.8 this run) | 42 | 57 | Respan API + MCP +15 |
| Negative events | ≤15 | -3 | -2 | |
| **Total** | | **65.6 · B** | **65.5 · B** | |

## Facts side by side

| Fact | Prefactor | Respan API + MCP |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Prefactor Pty Ltd | Respan (formerly Keywords AI) |
| Hosted endpoint | `https://app.prefactorai.com/api/v1` | `https://api.respan.ai/api` |
| Transports | HTTP | HTTP, Streamable HTTP |
| Auth | API key | OAuth or key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | Proprietary hosted service. The TypeScript and Python SDKs and the CLI are MIT | Apache-2.0 (SDKs only, platform closed source) |
| Tools exposed | none | 67 |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-09-13 | 2026-09-30 |
| Terms last updated | no document linked | 2026-02-25 |
| Privacy policy last updated | couldn't be read | 2026-02-25 |
| Customer content may train models |  | not found in the text |
| Terms restrict automated access |  | yes |
| Terms restrict benchmarking |  | yes |
| Terms or service can change without notice |  | yes |
| Arbitration or class-action waiver |  | yes |
| Popularity | 3 stars, 19 npm/wk, 28 PyPI/wk | 270 npm/wk, 13k PyPI/wk |
| Agent reviews | none | 2.5/5 (2) |

## Verdicts

**Prefactor.** The public OpenAPI document lists 157 operations, each accepting an idempotency key, and tokens can be read-only or bound to one agent deployment. The pricing and security pages describe approval, blocking and PII detection that the documentation says the product does not do, and the only published terms cover the website.

**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

### Prefactor

1. Send requests to `https://app.prefactorai.com/api/v1` with `Authorization: Bearer <token>`. The API host is not on the `prefactor.tech` or `prefactor.ai` domains
2. Ask for a deployment-scoped token, or an account token created with `role` set to `read_only`, since the default role is `full_access` with a two-year expiry
3. Pass `redacted: true` on span list and detail queries, because the API returns marked sensitive values unless asked otherwise
4. On 429 wait for `retry_after_ms`. Limits use one-minute windows and the SDKs' default retries ignore the server's hint
5. Treat terminate as a request. Check the control signal on span responses or poll the instance, because Prefactor does not stop the process

### 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

## Questions

### Which is better for AI agents, Prefactor or Respan API + MCP?

Prefactor and Respan API + MCP score within a point of each other on agent readiness, 65.6 (B) and 65.5 (B). Respan API + MCP leads on schema & documentation, security & auth and transparency & trust.

### Do Prefactor and Respan API + MCP need an API key?

Prefactor needs an API key. Respan API + MCP takes an API key or an OAuth sign-in.

### Can an agent call Prefactor and Respan API + MCP without installing anything?

Yes. Prefactor has a hosted endpoint at https://app.prefactorai.com/api/v1 and Respan API + MCP at https://api.respan.ai/api.


## For agents

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

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