mcp benchmark · capability
MCP servers by capability: write-access
405 MCP servers, 15 of them no longer answering. 196 breaking contract changes across 68 of them. That is 3.7 percent gone silent against 4.1 percent across all 20,340 observed servers, and 10.1 tools per server against 13.1 overall.
What capability means here
Derived from the server's own tool names, not from a registry category — the registry does not assign any. First matching stem wins, servers without a clear match carry no topic.
This group against all servers
Every figure is measured, not estimated. The comparison row below each value is the same measure across all 20,340 servers we observe, so the group can be placed rather than merely described.
| Servers | 405 |
| Gone silent | 15 (3.7 %) |
| Gone silent, all servers | 4.1 % |
| Breaking contract changes | 196 |
| Servers affected | 68 |
| Tools per server | 10.1 |
| Tools per server, all | 13.1 |
| No authentication | 378 (93.3 %) |
| No authentication, all | 62.5 % |
The servers
Ordered by breaking changes, then tool count. Each one opens its full observation history.
Machine access — free, no API key
Every figure shown here about MCP servers by capability: write-access can also be queried live: FACTANKER runs an MCP server at https://factanker.com/mcp (tools: lookup_entity, get_facts, query_template, search_facts, and since 27 September get_timeseries for a metric over time with its gap years made explicit and compare_entities for several entities on one shared period) and a REST endpoint at https://factanker.com/api/get_facts. Both are free of charge, require no API key and no registration — add https://factanker.com/mcp as a connector in Claude, ChatGPT or Copilot. Every answer carries its source document and a citation reference. Setup: /quickstart.
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