Select functions fail to import: `conv mcp tool input schema fail(unmarshal)`

[mgh14]

Description

Some operations of git-mcp-server fail to register with the MCP host. Each operation fails with the following warning structure:

Warning: Failed to load MCP server 'git-mcp-server': conv mcp tool input schema fail(unmarshal): json: cannot unmarshal number into Go struct field SchemaBis.properties.exclusiveMinimum of type bool, tool name: <tool operation here>

Furthermore, each warning stops the registration of any other operations not previously registered. Pictured below is an invocation of /tools to show which operations are actually available on the server, immediately after experiencing the warning for git_cherry_pick:

So, for git_cherry_pick this means that any operation named alphabetically after git_ch (e.g. git_commit, git_init) doesn't attempt to register with the host at all. Note that adding each of the affected operations to the excludedTools property in MCP configuration gets rid of the associated warning, but of course doesn't load that operation.

I'm using ollama and mcphost–admittedly this issue could have nothing to do with git-mcp-server (apologies if that's the case!!), but the warning message suggests that the tool input json schema itself can't be parsed, choking on properties.exclusiveMinimum.

Affected Operations

• git_cherry_pick
• git_clone
• git_fetch
• git_log
• git_reflog

Warning: Failed to load MCP server 'git-mcp-server': conv mcp tool input schema fail(unmarshal): json: cannot unmarshal number into Go struct field SchemaBis.properties.exclusiveMinimum of type bool, tool name: git_cherry_pick

Warning: Failed to load MCP server 'git-mcp-server': conv mcp tool input schema fail(unmarshal): json: cannot unmarshal number into Go struct field SchemaBis.properties.exclusiveMinimum of type bool, tool name: git_clone

Warning: Failed to load MCP server 'git-mcp-server': conv mcp tool input schema fail(unmarshal): json: cannot unmarshal number into Go struct field SchemaBis.properties.exclusiveMinimum of type bool, tool name: git_fetch

Warning: Failed to load MCP server 'git-mcp-server': conv mcp tool input schema fail(unmarshal): json: cannot unmarshal number into Go struct field SchemaBis.properties.exclusiveMinimum of type bool, tool name: git_log

Warning: Failed to load MCP server 'git-mcp-server': conv mcp tool input schema fail(unmarshal): json: cannot unmarshal number into Go struct field SchemaBis.properties.exclusiveMinimum of type bool, tool name: git_reflog

Steps to Reproduce

1. Build mcp-git-server: bun install @cyanheads/git-mcp-server@latest
2. Specify the following MCP config in the host (disregard the excludedTools property; I included that to make the warnings go away):

3. Start the Ollama layer: ollama serve
4. Run the MCP host: mcphost --debug -m ollama:gpt-oss:20b
5. The host starts but displays the warning, and fails to register any of the subsequent operations

Environment

OS: Mac Sonoma 14.7.5

Host: mcphost v0.31.4

Git: 2.39.5

Node.js: v24.2.0

npm: 11.3.0

bun: 1.3.3

MCP Git Server: 2.5.8

---

Any help appreciated, and apologies again if this isn't an issue with the git server. TIA! 🙏

[cyanheads]

Thanks for the detailed report - this helped track down the issue quickly.

Root Cause:
This was a JSON Schema draft compatibility issue. Zod's .positive() validator outputs "exclusiveMinimum": 0 (Draft 7 numeric format), but Go's JSON Schema parser expects "exclusiveMinimum": true (Draft 4 boolean format), causing the unmarshal error.

Affected Fields:

Tool	Field
git_cherry_pick	mainline
git_clone	depth
git_fetch	depth
git_log	maxCount
git_reflog	maxCount

The Fix:
Replaced .positive() with .min(1) - semantically equivalent for integers, but outputs "minimum": 1 which is universally compatible across all JSON Schema drafts.

Before:

"exclusiveMinimum": 0,
"maximum": 9007199254740991

After:

"minimum": 1,
"maximum": 1000

Added 16 regression tests to prevent this from recurring. Fix included in v2.6.2.

Let me know if you run into any other issues after updating!