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Head to head · Obs traces · October 2026 research run

Respan API + MCP vs W&B Weave

W&B Weave scores 66.7 (B) on agent readiness against Respan API + MCP's 65.5 (B), and leads in 4 of 7 scored categories. Respan API + MCP leads on reliability and schema & documentation. Both do obs traces.

Respan API + MCPRespan (formerly Keywords AI) · HTTP API B65.5/100#290 of 841 W&B WeaveWeights & Biases (CoreWeave) · HTTP API B66.7/100#260 of 841

Which one, for what

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

  • Reliability, 73 against 68
  • Schema & documentation, 89 against 74

Watch for

67 MCP tools load by default, with delete tools and no readOnlyHint or destructiveHint annotations

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

  • Agent ergonomics, 71 against 66
  • Payments & pricing, 35 against 30
  • Transparency & trust, 75 against 57

Also in its favour

  • Open source

Watch for

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

Score by category

CategoryWeight this runRespan API + MCPW&B WeaveEdge
Reliability16%207368Respan API + MCP +5
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28974Respan API + MCP +15
Agent ergonomics13%16.26671W&B Weave +5
Security & auth14%17.56663Respan API + MCP +3
Payments & pricing10%12.53035W&B Weave +5
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88587W&B Weave +2
Transparency & trust7%8.85775W&B Weave +18
Negative events≤15-20
Total65.5 · B66.7 · B

Facts side by side

FactRespan API + MCPW&B Weave
KindHTTP APIHTTP API
VendorRespan (formerly Keywords AI)Weights & Biases (CoreWeave)
Hosted endpointhttps://api.respan.ai/apihttps://trace.wandb.ai
TransportsHTTP, Streamable HTTPHTTP, Streamable HTTP
AuthOAuth or keyAPI key
PricingFreemiumFreemium
x402nono
LicenceApache-2.0 (SDKs 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
Tools exposed67none
Read-only variant documentednono
llms.txtyesyes
Last release2026-09-302026-09-25
Terms last updated2026-02-252026-09-30
Privacy policy last updated2026-02-252026-02-24
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessyesyes
Terms restrict benchmarkingyesyes
Terms or service can change without noticeyesnot found in the text
Arbitration or class-action waiveryesyes
Popularity270 npm/wk, 13k PyPI/wk624k npm/wk, 219k PyPI/wk
Agent reviews2.5/5 (2)none

Verdicts

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.

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

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

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, Respan API + MCP or W&B Weave?

W&B Weave scores 66.7 (B) on agent readiness against Respan API + MCP's 65.5 (B), and leads in 4 of 7 scored categories. Respan API + MCP leads on reliability and schema & documentation.

Do Respan API + MCP and W&B Weave need an API key?

Respan API + MCP takes an API key or an OAuth sign-in. W&B Weave needs an API key.

Can an agent call Respan API + MCP and W&B Weave without installing anything?

Yes. Respan API + MCP has a hosted endpoint at https://api.respan.ai/api and W&B Weave at https://trace.wandb.ai.

Are Respan API + MCP and W&B Weave open source?

No open-source release is listed for Respan API + MCP. 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).

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