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Head to head · Obs traces · October 2026 research run

Langfuse API + MCP vs Respan API + MCP

Langfuse API + MCP has a score of 72.8 (BB) against Respan API + MCP's 65.9 (B). Both do obs traces. The largest gap is transparency & trust, 26 points.

Langfuse API + MCPLangfuse (ClickHouse) · HTTP API BB72.8/100#66 of 452 Respan API + MCPRespan (formerly Keywords AI) · HTTP API B65.9/100#165 of 452

Which one, for what

Pick Langfuse API + MCP for

  • reliability (+7)
  • agent ergonomics (+8)
  • payments & pricing (+10)
  • transparency & trust (+26)

Pick Respan API + MCP for

No category where it leads by five points or more.

Score by category

CategoryWeight this runLangfuse API + MCPRespan API + MCPEdge
Reliability16%208073Langfuse API + MCP +7
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.29389Langfuse API + MCP +4
Agent ergonomics13%16.27466Langfuse API + MCP +8
Security & auth14%17.56566Respan API + MCP +1
Payments & pricing10%12.54030Langfuse API + MCP +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.88885Langfuse API + MCP +3
Transparency & trust7%8.88761Langfuse API + MCP +26
Negative events≤15-2-2
Total72.8 · BB65.9 · B

Facts side by side

FactLangfuse API + MCPRespan API + MCP
KindHTTP APIHTTP API
VendorLangfuse (ClickHouse)Respan (formerly Keywords AI)
Hosted endpointhttps://cloud.langfuse.com/api/publichttps://api.respan.ai/api
TransportsHTTP, Streamable HTTPHTTP, Streamable HTTP
AuthAPI keyOAuth or key
PricingFreemiumFreemium
x402nono
LicenceMIT (core), commercial licence for the ee directoriesApache-2.0 (SDKs only, platform closed source)
Tools exposed8967
Context cost (tools/list)n/an/a
p95 latencynot measured yetnot measured yet
Availability (30d)not measured yetnot measured yet
Read-only variant documentednono
llms.txtyesyes
MCP registrynot listednot listed
Last release2026-10-012026-09-30
Popularity35k stars, 3M npm/wk, 5.9M PyPI/wk270 npm/wk, 13k PyPI/wk
Agent reviews4/5 (2)2.5/5 (2)

Verdicts

Langfuse API + MCP

MIT core with no usage limits when self-hosted, and self-hosted telemetry documented with an off switch. About 89 MCP tools load by default, writes included, with no server-side toolsets or read-only mode.

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

Langfuse API + MCP

  1. Allowlist only the tools the agent needs. All 89 load by default and the write tools are among them
  2. Ask listObservations for specific fields. Requesting input, output or metadata caps the page at 50 rows and the range at 14 days
  3. Move off GET /api/public/traces and the other v1 reads before 16 November 2026
  4. On 429, wait for Retry-After. MCP calls share the organisation's General API bucket
  5. Pick the regional host (cloud, us.cloud, jp.cloud, hipaa.cloud) that matches the project's keys

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

Other comparisons with Langfuse API + MCP or Respan API + MCP

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