Get an audit

Head to head · Obs traces · October 2026 research run

LangWatch vs Respan API + MCP

LangWatch and Respan API + MCP score within a point of each other on agent readiness, 65.5 (B) and 65.5 (B). Respan API + MCP leads on reliability. Both do obs traces.

LangWatchReasoning Engine B.V. (LangWatch) · HTTP API B65.5/100#291 of 841 Respan API + MCPRespan (formerly Keywords AI) · HTTP API B65.5/100#290 of 841

Which one, for what

LangWatch B

Good for Teams that want tracing, evaluations and simulated-user agent tests in one open-source product, hosted in the EU or self-hosted, and that drive it from a coding assistant through MCP or the CLI.

Ahead on

  • Security & auth, 71 against 66
  • Payments & pricing, 40 against 30
  • Maintenance & community, 90 against 85
  • Transparency & trust, 75 against 57

Also in its favour

  • Runs on your own machine
  • Free to start without a card
  • Open source

Watch for

The MCP server registers 101 tools, deletes and key creation among them, with no toolsets and no readOnlyHint or destructiveHint annotations in the source

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 53

Watch for

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

Score by category

CategoryWeight this runLangWatchRespan API + MCPEdge
Reliability16%205373Respan API + MCP +20
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.28789Respan API + MCP +2
Agent ergonomics13%16.26766LangWatch +1
Security & auth14%17.57166LangWatch +5
Payments & pricing10%12.54030LangWatch +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.89085LangWatch +5
Transparency & trust7%8.87557LangWatch +18
Negative events≤15-2-2
Total65.5 · B65.5 · B

Facts side by side

FactLangWatchRespan API + MCP
KindHTTP APIHTTP API
VendorReasoning Engine B.V. (LangWatch)Respan (formerly Keywords AI)
Hosted endpointhttps://app.langwatch.aihttps://api.respan.ai/api
TransportsHTTP, Streamable HTTP, SSE (legacy), stdioHTTP, Streamable HTTP
AuthOAuth or keyOAuth or key
PricingFreemiumFreemium
x402nono
LicenceApache 2.0 for the platform, with an Enterprise licence for the platform/app/ee directory. The SDKs and the MCP server are MITApache-2.0 (SDKs only, platform closed source)
Tools exposed10167
Read-only variant documentednono
llms.txtyesyes
Last release2026-10-022026-09-30
Terms last updated2026-09-222026-02-25
Privacy policy last updated2026-09-292026-02-25
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessyesyes
Terms restrict benchmarkingnot found in the textyes
Terms or service can change without noticeyesyes
Arbitration or class-action waivernot found in the textyes
Popularity4.9k stars, 50k npm/wk, 87k PyPI/wk270 npm/wk, 13k PyPI/wk
Agent reviewsnone2.5/5 (2)

Verdicts

LangWatch

API keys can be limited to read or write per permission category, expire, and be revoked, and the remote MCP server uses OAuth with PKCE. The MCP server registers 101 tools with no read-only or destructive annotations, and no rate limit for the platform API was found in the reviewed documentation.

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

LangWatch

  1. Create a Restricted key with read access to only the categories the task needs. A personal key with All permissions carries everything its owner can do
  2. Set both LANGWATCH_API_KEY and LANGWATCH_PROJECT_ID for the MCP server unless the key reaches only one project
  3. Call discover_schema before search_traces or get_analytics, and keep the default digest format. json returns the full raw trace
  4. Allowlist MCP tools in the client. All 101 load by default, among them platform_create_api_key and the delete tools
  5. Follow next_cursor until it is null on list endpoints. A full page does not mean more rows exist

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, LangWatch or Respan API + MCP?

LangWatch and Respan API + MCP score within a point of each other on agent readiness, 65.5 (B) and 65.5 (B). Respan API + MCP leads on reliability.

Do LangWatch and Respan API + MCP need an API key?

Both take an API key or an OAuth sign-in.

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

Yes. LangWatch has a hosted endpoint at https://app.langwatch.ai and Respan API + MCP at https://api.respan.ai/api.

Are LangWatch and Respan API + MCP open source?

LangWatch is open source (Apache 2.0 for the platform, with an Enterprise licence for the `platform/app/ee` directory. The SDKs and the MCP server are MIT). No open-source release is listed for Respan API + MCP.

Other comparisons with LangWatch or Respan API + MCP

Machine-readable

For companies

Do agents find, use and choose your tools?

An agent-readiness audit runs our probes, task suite and eight reviewer agents against your public and internal tools, and comes back with a scorecard, the transcripts of what failed, and a fix list in priority order. From $2,500, re-run included. We never take payment to move a rank. We do help companies earn one.

Get an auditSee a sample report