Magic MCP vs SpanHound
A side-by-side look at the Magic MCP and SpanHound MCP servers: transport, auth, tools, quality signals, and the config to install either one in Claude, Cursor, Windsurf or VS Code.
S
SpanHoundDeveloper ToolsCapture local agent traces and inspect failures, approvals, and run comparisons.47FairAuth: no auth requiredVerdict: choose Magic MCP for developer tools work as a local process; choose SpanHound for developer tools. You can also run both side by side in one mcpServers block.
Which MCP server should you choose?
Choose Magic MCP when
- You need dedicated capabilities in the Developer Tools domain.
- You prefer a local stdio subprocess transport.
- Its auth model fits you: API key required.
- You have the keys it needs:
TWENTY_FIRST_API_KEY, API_KEY_21ST.
SChoose SpanHound when
- You need dedicated capabilities in the Developer Tools domain.
- Its auth model fits you: No auth required.
- You want tools like
list_runs, run_summary, span_tree.
Feature & specification comparison
Rows where the two servers differ are marked.
| Spec | S SpanHound | |
|---|---|---|
| Category | Developer Tools | Developer Tools |
| Quality signal | 53/100 · Good | 47/100 · Fair |
| Install command | Confirmed | Not confirmed yet |
| Transport | Local subprocess (stdio) | — |
| Auth | API key required | No auth required |
| Pricing | Paid service | Free |
| Required env vars | TWENTY_FIRST_API_KEYAPI_KEY_21ST | None listed |
Tools & capabilities
Magic MCP tools
No tool names declared yet. Check the project README from the listing page.
SpanHound tools 12
list_runsStarting out — recent runs with task, model, duration, cost, decision countsrun_summaryOne run at a glance (accepts trace-id prefix)span_tree"What did the agent actually do?" — nested shape of the runslowest_spans"Why was it slow?" — top-k spans by durationapproval_logHITL audit — every approve/deny/**edit**, who decided, and *the rationale*token_usageCost questions — aggregated across runs or per-runsearch_spansFind spans by tool name, file path, "denied", …failure_reportFind actionable, bounded, redacted errors and failed tool calls.tool_statsRank tools by volume, error rate, denials, and latency.security_auditAudit caller identity, tenant, server provenance, risk, and approval evidence.recent_activityPoll new spans with a cursor while a run is active.compare_runsCompare selected traces for regressions across models or versions.
Ready-to-paste client configs
Paste either block (or both) into your client config, e.g. claude_desktop_config.json or ~/.cursor/mcp.json. We only show a config when the install command is confirmed.
Magic MCP
{
"mcpServers": {
"21st-dev-magic-mcp": {
"command": "npx",
"args": [
"-y",
"@21st-dev/cli@latest"
],
"env": {
"TWENTY_FIRST_API_KEY": "YOUR_TWENTY_FIRST_API_KEY_HERE",
"API_KEY_21ST": "YOUR_API_KEY_21ST_HERE"
}
}
}
}
SpanHound
No confirmed install command for SpanHound yet — follow the setup steps linked from its listing page rather than a guessed package name.
Frequently asked questions
Magic MCP is categorized under Developer Tools and uses a local stdio subprocess. SpanHound belongs to Developer Tools and uses an install path we have not confirmed yet. Pick Magic MCP for developer tools work and SpanHound for developer tools.
Copy the mcpServers block from the config section on this page into your client's config (for example claude_desktop_config.json or ~/.cursor/mcp.json), then fully restart the client. SpanHound has no confirmed install command yet — follow its own setup instructions.
Magic MCP is listed as a paid service. Auth: api key required. SpanHound is listed as free. Auth: no auth required. If a server needs environment variables such as API keys, define them under the env key in your client's MCP config.
Yes. MCP clients support multiple servers: add 21st-dev-magic-mcp and spanhound as separate keys in the same mcpServers object, and your assistant will call tools from either one.
On AllMCPs, Magic MCP has a quality signal of 53/100 (Good) with 16 views, 1 installs and 5,997 GitHub stars. SpanHound has 47/100 (Fair) with 0 views, 0 installs and 0 GitHub stars.