fix(mcp): only advertise list-resource meta-tools when resources exist#3963
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h3c-hexin wants to merge 1 commit into
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fix(mcp): only advertise list-resource meta-tools when resources exist#3963h3c-hexin wants to merge 1 commit into
h3c-hexin wants to merge 1 commit into
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`list_mcp_resources` and `list_mcp_resource_templates` were injected whenever any MCP server was configured, regardless of whether any server actually exposes resources or templates. For tools-only servers this leaves the model with meta-tools that can only ever return empty results, wasting a tool slot and prompt tokens on every request. Gate each meta-tool on its own non-empty collection, mirroring the existing `mcp_read_resource` guard.
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Problem
list_mcp_resourcesandlist_mcp_resource_templatesare injected into the model-visible tool catalog whenever any MCP server is configured (!self.config.servers.is_empty()), regardless of whether the configured servers actually expose any resources or resource templates.For tools-only MCP servers — common in practice, e.g. a server that only implements
tools/list+tools/calland returns-32601 method not foundforresources/list— this means the model is permanently offered two meta-tools that can only ever return empty results. That wastes a tool slot and prompt tokens on every request, and can nudge smaller models into calling a no-op tool.Fix
Gate each meta-tool on its own non-empty collection (
all_resources()/all_resource_templates()), mirroring the existingmcp_read_resourceguard immediately below (!resources.is_empty()). Servers that do expose resources / templates are unaffected; tools-only servers simply no longer get the empty meta-tools.Notes
defer_loadingcatalog tests constructlist_mcp_resourcesdirectly viaapi_tool(...), andMcpPool::is_mcp_tool(...)classification is independent of injection.cargo check -p codewhale-tuipasses.