HISTOR: 45% of remote MCP servers changed tool definitions in four weeks

HISTOR, a public log that reads the tool lists of every remote MCP server in the official registry daily, has released its first snapshot as open data. Between 24 September and 20 October, 4,926 of 10,929 servers (45%) served a different tool list at least once, across 23,821 recorded changes.

• 4,926 of 10,929 servers (45%) changed their tool list between 24 September and 20 October
• 2,036 servers edited an existing tool's description, 1,180 added a tool and 336 removed one
• 59% of changes (14,164) touch at least one description the model reads as guidance
• 2,719 changes altered only digits in a description, 2,493 of them from one publisher