mcp-client-capabilities

Provides a language-friendly distribution of a single curated JSON database (mcp-clients.json) listing MCP client names, metadata, and capability flags compatible with MCP client capability schemas. Intended for MCP servers to decide how to present resources/tools/prompts/instructions based on known client feature support.

Evaluated Mar 30, 2026 (21d ago)
Homepage ↗ Repo ↗ DevTools mcp model-context-protocol capabilities client-registry typescript python json compatibility-matrix
⚙ Agent Friendliness
66
/ 100
Can an agent use this?
🔒 Security
96
/ 100
Is it safe for agents?
⚡ Reliability
42
/ 100
Does it work consistently?

Score Breakdown

⚙ Agent Friendliness

MCP Quality
0
Documentation
88
Error Messages
0
Auth Simplicity
100
Rate Limits
0

🔒 Security

TLS Enforcement
100
Auth Strength
100
Scope Granularity
100
Dep. Hygiene
70
Secret Handling
100

No authentication or data collection described; package serves static capability metadata. Main security considerations are supply-chain integrity (verify npm/pypi provenance) and treating the data as non-authoritative per runtime handshake. TLS is not directly applicable since no network API is described, but typical package download occurs over HTTPS.

⚡ Reliability

Uptime/SLA
0
Version Stability
60
Breaking Changes
60
Error Recovery
50
AF Security Reliability

Best When

When you’re implementing MCP server logic and want a maintained reference table to complement/triage the official initialize handshake capabilities.

Avoid When

When you need real-time updates, authoritative per-instance capability negotiation beyond initialize, or an API with query/update endpoints.

Use Cases

  • MCP server capability-aware behavior (e.g., offer alternate tools or instructions based on client support)
  • Building UI/agents that need to understand which MCP client features are likely available
  • Offline validation/testing and code generation against a maintained client capability matrix
  • Cross-language consumption of client capability metadata (TS/Python) via packaged exports or raw JSON URL

Not For

  • A live registry or query service (the data is static JSON, not a network API)
  • Security authorization/token management between client and server
  • Guaranteeing actual runtime capability support of a specific client version (it’s a best-effort index, servers should rely on initialize params.capabilities)

Interface

REST API
No
GraphQL
No
gRPC
No
MCP Server
No
SDK
Yes
Webhooks
No

Authentication

OAuth: No Scopes: No

No authentication—package is a published data/library artifact.

Pricing

Free tier: No
Requires CC: No

No pricing information indicated; appears to be free/open-source distribution.

Agent Metadata

Pagination
none
Idempotent
False
Retry Guidance
Not documented

Known Gotchas

  • This is not a network service; integration is via static JSON/library exports.
  • Servers should not treat the indexed capabilities as authoritative—README stresses prioritizing initialize.params.capabilities and ignoring out-of-date protocolVersion mismatches.
  • Capability fields are optional; code should handle missing properties (e.g., resources/prompts/tools might be absent).

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Scores are editorial opinions as of 2026-03-30.

8642
Packages Evaluated
17761
Need Evaluation
586
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