32cf71de3aChange the design of tool handlers by removing genericity from the common path. - `ToolHandler` gets the args as a `json.RawMessage`. Using Server.AddTool does no unmarshaling or schema validation. - `ToolHandlerFor`, installed with `AddTool`, are the only generic pieces. TODO: uncomment and fix some tests
64 lines
2.2 KiB
Go
64 lines
2.2 KiB
Go
// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
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// Use of this source code is governed by an MIT-style
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// license that can be found in the LICENSE file.
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package mcp
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import (
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"bytes"
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"context"
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"encoding/json"
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"fmt"
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"github.com/google/jsonschema-go/jsonschema"
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)
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// A ToolHandler handles a call to tools/call.
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// [CallToolParams.Arguments] will contain a map[string]any that has been validated
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// against the input schema.
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type ToolHandler func(context.Context, *ServerRequest[*CallToolParams]) (*CallToolResult, error)
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// A ToolHandlerFor handles a call to tools/call with typed arguments and results.
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type ToolHandlerFor[In, Out any] func(context.Context, *ServerRequest[*CallToolParams], In) (*CallToolResult, Out, error)
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// A serverTool is a tool definition that is bound to a tool handler.
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type serverTool struct {
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tool *Tool
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handler ToolHandler
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}
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// unmarshalSchema unmarshals data into v and validates the result according to
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// the given resolved schema.
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func unmarshalSchema(data json.RawMessage, resolved *jsonschema.Resolved, v any) error {
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// TODO: use reflection to create the struct type to unmarshal into.
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// Separate validation from assignment.
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// Disallow unknown fields.
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// Otherwise, if the tool was built with a struct, the client could send extra
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// fields and json.Unmarshal would ignore them, so the schema would never get
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// a chance to declare the extra args invalid.
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dec := json.NewDecoder(bytes.NewReader(data))
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dec.DisallowUnknownFields()
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if err := dec.Decode(v); err != nil {
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return fmt.Errorf("unmarshaling: %w", err)
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}
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// TODO: test with nil args.
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if resolved != nil {
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if err := resolved.ApplyDefaults(v); err != nil {
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return fmt.Errorf("applying defaults from \n\t%s\nto\n\t%s:\n%w", schemaJSON(resolved.Schema()), data, err)
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}
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if err := resolved.Validate(v); err != nil {
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return fmt.Errorf("validating\n\t%s\nagainst\n\t %s:\n %w", data, schemaJSON(resolved.Schema()), err)
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}
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}
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return nil
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}
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// schemaJSON returns the JSON value for s as a string, or a string indicating an error.
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func schemaJSON(s *jsonschema.Schema) string {
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m, err := json.Marshal(s)
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if err != nil {
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return fmt.Sprintf("<!%s>", err)
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}
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return string(m)
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}
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