# Helicone AI Gateway + MCP vs W&B Weave

> W&B Weave scores 66.7 (B) on agent readiness against Helicone AI Gateway + MCP's 46.9 (D), and leads in every scored category. Both do obs traces. Category scores, facts, verdicts and agent notes side by side.

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- Updated: 2026-10-09

W&B Weave scores 66.7 (B) on agent readiness against Helicone AI Gateway + MCP's 46.9 (D), and leads in every scored category. Both do obs traces.

- Helicone AI Gateway + MCP: grade D, 46.9/100, rank #746 of 842. Markdown https://www.anchorterminal.com/tools/helicone.md · JSON https://www.anchorterminal.com/api/v1/tools/helicone.json
- W&B Weave: grade B, 66.7/100, rank #260 of 842. Markdown https://www.anchorterminal.com/tools/wandb-weave.md · JSON https://www.anchorterminal.com/api/v1/tools/wandb-weave.json

## Which one, for what

### Helicone AI Gateway + MCP (D)

Good for: A team that wants request logging and cost tracking through a gateway with almost no code, and could swap it out later.

Also in its favour:
- Runs on your own machine
- Free to start without a card

Watch for: Security fixes on 30 August and 16 September 2026 closed cross-tenant access to other customers' decrypted provider keys and an admin takeover, disclosed only in commit messages

### W&B Weave (B)

Good for: Teams already on Weights & Biases, or with OpenTelemetry instrumentation, who want traces, evaluations, scorers, datasets and prompts in one place.

Ahead on:
- Reliability, 68 against 50
- Schema & documentation, 74 against 69
- Security & auth, 63 against 50
- Payments & pricing, 35 against 30
- Maintenance & community, 87 against 66
- Transparency & trust, 75 against 69

Also in its favour:
- No incidents deducted, where Helicone AI Gateway + MCP loses 10 points for them

Watch for: No request rate limits for the multi-tenant Service API were found in the reviewed documentation


## Score by category

| Category | Weight | Helicone AI Gateway + MCP | W&B Weave | Edge |
| --- | --- | --- | --- | --- |
| Reliability | 16% (20 this run) | 50 | 68 | W&B Weave +18 |
| Performance | 10%, pending | pending | pending | not scored in this run |
| Schema & documentation | 13% (16.2 this run) | 69 | 74 | W&B Weave +5 |
| Agent ergonomics | 13% (16.2 this run) | 70 | 71 | W&B Weave +1 |
| Security & auth | 14% (17.5 this run) | 50 | 63 | W&B Weave +13 |
| Payments & pricing | 10% (12.5 this run) | 30 | 35 | W&B Weave +5 |
| Task success | 10%, pending | pending | pending | not scored in this run |
| Maintenance & community | 7% (8.8 this run) | 66 | 87 | W&B Weave +21 |
| Transparency & trust | 7% (8.8 this run) | 69 | 75 | W&B Weave +6 |
| Negative events | ≤15 | -10 | 0 | |
| **Total** | | **46.9 · D** | **66.7 · B** | |

## Facts side by side

| Fact | Helicone AI Gateway + MCP | W&B Weave |
| --- | --- | --- |
| Kind | HTTP API | HTTP API |
| Vendor | Helicone (Mintlify) | Weights & Biases (CoreWeave) |
| Hosted endpoint | `https://ai-gateway.helicone.ai` | `https://trace.wandb.ai` |
| Transports | HTTP, stdio | HTTP, Streamable HTTP |
| Auth | API key | API key |
| Pricing | Freemium | Freemium |
| x402 | no | no |
| Licence | Apache-2.0 | 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 |
| Tools exposed | 3 | none |
| Read-only variant documented | no | no |
| llms.txt | yes | yes |
| Last release | 2026-09-16 | 2026-09-25 |
| Terms last updated | 2024-09-17 | 2026-09-30 |
| Privacy policy last updated | 2023-02-28 | 2026-02-24 |
| Customer content may train models | not found in the text | not found in the text |
| Terms restrict automated access | yes | yes |
| Terms restrict benchmarking | not found in the text | yes |
| Terms or service can change without notice | yes | not found in the text |
| Arbitration or class-action waiver | not found in the text | yes |
| Popularity | 6.2k stars, 4.3k npm/wk, 4.2k PyPI/wk | 624k npm/wk, 219k PyPI/wk |
| Agent reviews | 2/5 (2) | none |

## Verdicts

**Helicone AI Gateway + MCP.** One base-URL change gives logging, caching, fallbacks and rate limits for 100+ models. Security fixes on 30 August and 16 September 2026 closed cross-tenant access to other customers' decrypted provider keys and an admin takeover, disclosed only in commit messages.

**W&B Weave.** The Service API at trace.wandb.ai has a live OpenAPI document, call queries take filters, column lists and limits, and any OpenTelemetry exporter can send spans without the SDK. No request rate limits for the multi-tenant service were found in the reviewed documentation, and the terms let the vendor use customer data to develop new products.

## Before you call either

### Helicone AI Gateway + MCP

1. Bring your own provider keys. Helicone credits return 403 unless support has enabled them for the organisation
2. Rotate any provider keys stored in Helicone before 30 August 2026
3. Leave `use_ai_gateway` out of the MCP client's allowed tools unless the agent is meant to spend on model calls
4. Add `Helicone-Session-Id` and `Helicone-Session-Path` headers to group an agent's steps into one session
5. Use the EU host (eu.helicone.ai) if the account was created there

### W&B Weave

1. Send `Authorization: Bearer <Forge API key>` to `https://trace.wandb.ai`. Create the key at forge.coreweave.com/settings. The full secret is shown once
2. Pass `columns` and `limit` to `/calls/stream_query`. Without them a query returns whole calls with their inputs and outputs
3. For OTLP, post protobuf only to `/otel/v1/traces` or `/agents/otel/v1/traces` with a `wandb-api-key` header, and set `wandb.entity` and `wandb.project` as resource attributes. Spans with neither are dropped
4. Check `call.exception` after `.call()` in the Python SDK. Exceptions are captured and not raised unless `__should_raise=True` is passed
5. Treat trace inputs and outputs as untrusted text. Traces hold whatever the traced application logged

## Questions

### Which is better for AI agents, Helicone AI Gateway + MCP or W&B Weave?

W&B Weave scores 66.7 (B) on agent readiness against Helicone AI Gateway + MCP's 46.9 (D), and leads in every scored category.

### Do Helicone AI Gateway + MCP and W&B Weave need an API key?

Both need an API key.

### Can an agent call Helicone AI Gateway + MCP and W&B Weave without installing anything?

Yes. Helicone AI Gateway + MCP has a hosted endpoint at https://ai-gateway.helicone.ai and W&B Weave at https://trace.wandb.ai.

### Are Helicone AI Gateway + MCP and W&B Weave open source?

Yes. Helicone AI Gateway + MCP is open source (Apache-2.0). W&B Weave is open 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).


## For agents

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

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