Summary
The MCP server names defined in .mcp.json cause tool names to exceed the 64-character limit enforced by the Claude API, resulting in invalid_request_error when using the plugin.
Error
{"type":"error","error":{"type":"invalid_request_error","message":"messages.X.content.0.tool_result.content.0.tool_reference.tool_name: String should have at most 64 characters"}}
Root Cause
Claude Code prefixes MCP tool names with mcp__plugin_cloudflare_, then appends the server name and tool name. The current server names in .mcp.json create excessively long prefixes:
| Server Name |
Full Prefix |
Length |
cloudflare-docs |
mcp__plugin_cloudflare_cloudflare-docs__ |
41 |
cloudflare-workers-observability |
mcp__plugin_cloudflare_cloudflare-workers-observability__ |
56 |
cloudflare-workers-builds |
mcp__plugin_cloudflare_cloudflare-workers-builds__ |
49 |
When combined with tool names like query_worker_observability (26 chars), the total exceeds 64 characters.
Suggested Fix
Remove the redundant cloudflare- prefix from server names since it's already included in the plugin prefix:
{
"mcpServers": {
"docs": {
"command": "npx",
"args": ["mcp-remote", "https://docs.mcp.cloudflare.com/mcp"]
},
"observability": {
"command": "npx",
"args": ["mcp-remote", "https://observability.mcp.cloudflare.com/mcp"]
},
"builds": {
"command": "npx",
"args": ["mcp-remote", "https://builds.mcp.cloudflare.com/mcp"]
}
}
}
This would create prefixes of 29-38 characters, leaving ample room for tool names.
Environment
- Claude Code CLI
- Cloudflare skills plugin (commit 3f72589, 2026-01-28)
Summary
The MCP server names defined in
.mcp.jsoncause tool names to exceed the 64-character limit enforced by the Claude API, resulting ininvalid_request_errorwhen using the plugin.Error
Root Cause
Claude Code prefixes MCP tool names with
mcp__plugin_cloudflare_, then appends the server name and tool name. The current server names in.mcp.jsoncreate excessively long prefixes:cloudflare-docsmcp__plugin_cloudflare_cloudflare-docs__cloudflare-workers-observabilitymcp__plugin_cloudflare_cloudflare-workers-observability__cloudflare-workers-buildsmcp__plugin_cloudflare_cloudflare-workers-builds__When combined with tool names like
query_worker_observability(26 chars), the total exceeds 64 characters.Suggested Fix
Remove the redundant
cloudflare-prefix from server names since it's already included in the plugin prefix:{ "mcpServers": { "docs": { "command": "npx", "args": ["mcp-remote", "https://docs.mcp.cloudflare.com/mcp"] }, "observability": { "command": "npx", "args": ["mcp-remote", "https://observability.mcp.cloudflare.com/mcp"] }, "builds": { "command": "npx", "args": ["mcp-remote", "https://builds.mcp.cloudflare.com/mcp"] } } }This would create prefixes of 29-38 characters, leaving ample room for tool names.
Environment