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chore: separate the LoadSession function in the MCP loader #966

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Merged
merged 2 commits into from
May 7, 2025
Merged

chore: separate the LoadSession function in the MCP loader #966

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664d93c
chore: separate the LoadSession function in the MCP loader
thedadams May 6, 2025
bf651d1
Add the ability to specify allowed tools for MCP servers
thedadams May 7, 2025
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26 changes: 23 additions & 3 deletions pkg/mcp/loader.go
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Original file line number Diff line number Diff line change
Expand Up @@ -56,6 +56,7 @@ type ServerConfig struct {
BaseURL string `json:"baseURL,omitempty"`
Headers []string `json:"headers"`
Scope string `json:"scope"`
AllowedTools []string `json:"allowedTools"`
}

func (s *ServerConfig) GetBaseURL() string {
Expand Down Expand Up @@ -99,18 +100,31 @@ func (l *Local) Load(ctx context.Context, tool types.Tool) (result []types.Tool,
}

for server := range maps.Keys(servers.MCPServers) {
session, err := l.loadSession(servers.MCPServers[server])
tools, err := l.LoadTools(ctx, servers.MCPServers[server], tool.Name)
if err != nil {
return nil, fmt.Errorf("failed to load MCP session for server %s: %w", server, err)
}

return l.sessionToTools(ctx, session, tool.Name)
return tools, nil
}

// This should never happen, but just in case
return nil, fmt.Errorf("no MCP server configuration found in tool instructions: %s", configData)
}

func (l *Local) LoadTools(ctx context.Context, server ServerConfig, toolName string) ([]types.Tool, error) {
allowedTools := server.AllowedTools
// Reset so we don't start a new MCP server, no reason to if one is already running and the allowed tools change.
server.AllowedTools = nil

session, err := l.loadSession(server)
if err != nil {
return nil, err
}

return l.sessionToTools(ctx, session, toolName, allowedTools)
}

func (l *Local) Close() error {
if l == nil {
return nil
Expand Down Expand Up @@ -139,7 +153,9 @@ func (l *Local) Close() error {
return errors.Join(errs...)
}

func (l *Local) sessionToTools(ctx context.Context, session *Session, toolName string) ([]types.Tool, error) {
func (l *Local) sessionToTools(ctx context.Context, session *Session, toolName string, allowedTools []string) ([]types.Tool, error) {
allToolsAllowed := len(allowedTools) == 0 || slices.Contains(allowedTools, "*")

tools, err := session.Client.ListTools(ctx, mcp.ListToolsRequest{})
if err != nil {
return nil, fmt.Errorf("failed to list tools: %w", err)
Expand All @@ -149,6 +165,10 @@ func (l *Local) sessionToTools(ctx context.Context, session *Session, toolName s
var toolNames []string

for _, tool := range tools.Tools {
if !allToolsAllowed && !slices.Contains(allowedTools, tool.Name) {
continue
}

var schema openapi3.Schema

schemaData, err := json.Marshal(tool.InputSchema)
Expand Down
12 changes: 6 additions & 6 deletions pkg/tests/runner2_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -313,7 +313,7 @@ name: mcp
],
"type": "object"
},
"instructions": "#!sys.mcp.invoke.append_insight 607ca64476abf0288ef49061557243e43735fd4de4bc5fdcd51d93049ffa023e",
"instructions": "#!sys.mcp.invoke.append_insight c358c2eb93fa9a98631cd9e4f324d7b59f56aee11c7ae32a00984ad5844dc32c",
"id": "inline:append_insight",
"localTools": {
"append_insight": "inline:append_insight",
Expand Down Expand Up @@ -346,7 +346,7 @@ name: mcp
],
"type": "object"
},
"instructions": "#!sys.mcp.invoke.create_table 607ca64476abf0288ef49061557243e43735fd4de4bc5fdcd51d93049ffa023e",
"instructions": "#!sys.mcp.invoke.create_table c358c2eb93fa9a98631cd9e4f324d7b59f56aee11c7ae32a00984ad5844dc32c",
"id": "inline:create_table",
"localTools": {
"append_insight": "inline:append_insight",
Expand Down Expand Up @@ -379,7 +379,7 @@ name: mcp
],
"type": "object"
},
"instructions": "#!sys.mcp.invoke.describe_table 607ca64476abf0288ef49061557243e43735fd4de4bc5fdcd51d93049ffa023e",
"instructions": "#!sys.mcp.invoke.describe_table c358c2eb93fa9a98631cd9e4f324d7b59f56aee11c7ae32a00984ad5844dc32c",
"id": "inline:describe_table",
"localTools": {
"append_insight": "inline:append_insight",
Expand All @@ -403,7 +403,7 @@ name: mcp
"arguments": {
"type": "object"
},
"instructions": "#!sys.mcp.invoke.list_tables 607ca64476abf0288ef49061557243e43735fd4de4bc5fdcd51d93049ffa023e",
"instructions": "#!sys.mcp.invoke.list_tables c358c2eb93fa9a98631cd9e4f324d7b59f56aee11c7ae32a00984ad5844dc32c",
"id": "inline:list_tables",
"localTools": {
"append_insight": "inline:append_insight",
Expand Down Expand Up @@ -505,7 +505,7 @@ name: mcp
],
"type": "object"
},
"instructions": "#!sys.mcp.invoke.read_query 607ca64476abf0288ef49061557243e43735fd4de4bc5fdcd51d93049ffa023e",
"instructions": "#!sys.mcp.invoke.read_query c358c2eb93fa9a98631cd9e4f324d7b59f56aee11c7ae32a00984ad5844dc32c",
"id": "inline:read_query",
"localTools": {
"append_insight": "inline:append_insight",
Expand Down Expand Up @@ -538,7 +538,7 @@ name: mcp
],
"type": "object"
},
"instructions": "#!sys.mcp.invoke.write_query 607ca64476abf0288ef49061557243e43735fd4de4bc5fdcd51d93049ffa023e",
"instructions": "#!sys.mcp.invoke.write_query c358c2eb93fa9a98631cd9e4f324d7b59f56aee11c7ae32a00984ad5844dc32c",
"id": "inline:write_query",
"localTools": {
"append_insight": "inline:append_insight",
Expand Down