mcp: add prompt feature doc (#487)

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Jonathan Amsterdam 2025-09-18 12:27:02 -04:00 • committed by GitHub
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5 changed files with 193 additions and 4 deletions

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@ -13,7 +13,7 @@ The SDK supports this as follows:
**Client-side**: The SDK client always has the `roots.listChanged` capability.
To add roots to a client, use the
[`Client.AddRoots`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#AddRoots)
[`Client.AddRoots`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#Client.AddRoots)
and
[`Client.RemoveRoots`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#Client.RemoveRoots)
methods. If any servers are already [connected](protocol.md#lifecycle) to the

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@ -11,7 +11,93 @@
## Prompts
<!-- TODO -->
**Server-side**:
MCP servers can provide LLM prompt templates (called simply _prompts_) to clients.
Every prompt has a required name which identifies it, and a set of named arguments, which are strings.
Construct a prompt with a name and descriptions of its arguments.
Associated with each prompt is a handler that expands the template given values for its arguments.
Use [`Server.AddPrompt`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#Server.AddPrompt)
to add a prompt along with its handler.
If `AddPrompt` is called before a server is connected, the server will have the `prompts` capability.
If all prompts are to be added after connection, set [`ServerOptions.HasPrompts`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerOptions.HasPrompts)
to advertise the capability.
**Client-side**:
To list the server's prompts, call
Call [`ClientSession.Prompts`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientSession.Prompts) to get an iterator.
If needed, you can use the lower-level
[`ClientSession.ListPrompts`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientSession.ListPrompts) to list the server's prompts.
Call [`ClientSession.GetPrompt`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientSession.GetPrompt) to retrieve a prompt by name, providing
arguments for expansion.
Set [`ClientOptions.PromptListChangedHandler`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientOptions.PromptListChangedHandler) to be notified of changes in the list of prompts.
```go
func Example_prompts() {
ctx := context.Background()
promptHandler := func(ctx context.Context, req *mcp.GetPromptRequest) (*mcp.GetPromptResult, error) {
return &mcp.GetPromptResult{
Description: "Hi prompt",
Messages: []*mcp.PromptMessage{
{
Role: "user",
Content: &mcp.TextContent{Text: "Say hi to " + req.Params.Arguments["name"]},
},
},
}, nil
}
// Create a server with a single prompt.
s := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.0.1"}, nil)
prompt := &mcp.Prompt{
Name: "greet",
Arguments: []*mcp.PromptArgument{
{
Name: "name",
Description: "the name of the person to greet",
Required: true,
},
},
}
s.AddPrompt(prompt, promptHandler)
// Create a client.
c := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
// Connect the server and client.
t1, t2 := mcp.NewInMemoryTransports()
if _, err := s.Connect(ctx, t1, nil); err != nil {
log.Fatal(err)
}
cs, err := c.Connect(ctx, t2, nil)
if err != nil {
log.Fatal(err)
}
// List the prompts.
for p, err := range cs.Prompts(ctx, nil) {
if err != nil {
log.Fatal(err)
}
fmt.Println(p.Name)
}
// Get the prompt.
res, err := cs.GetPrompt(ctx, &mcp.GetPromptParams{
Name: "greet",
Arguments: map[string]string{"name": "Pat"},
})
if err != nil {
log.Fatal(err)
}
for _, msg := range res.Messages {
fmt.Println(msg.Role, msg.Content.(*mcp.TextContent).Text)
}
// Output:
// greet
// user Say hi to Pat
}
```
## Resources

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@ -10,7 +10,7 @@ The SDK supports this as follows:
**Client-side**: The SDK client always has the `roots.listChanged` capability.
To add roots to a client, use the
[`Client.AddRoots`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#AddRoots)
[`Client.AddRoots`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#Client.AddRoots)
and
[`Client.RemoveRoots`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#Client.RemoveRoots)
methods. If any servers are already [connected](protocol.md#lifecycle) to the

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@ -4,7 +4,27 @@
## Prompts
<!-- TODO -->
**Server-side**:
MCP servers can provide LLM prompt templates (called simply _prompts_) to clients.
Every prompt has a required name which identifies it, and a set of named arguments, which are strings.
Construct a prompt with a name and descriptions of its arguments.
Associated with each prompt is a handler that expands the template given values for its arguments.
Use [`Server.AddPrompt`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#Server.AddPrompt)
to add a prompt along with its handler.
If `AddPrompt` is called before a server is connected, the server will have the `prompts` capability.
If all prompts are to be added after connection, set [`ServerOptions.HasPrompts`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ServerOptions.HasPrompts)
to advertise the capability.
**Client-side**:
To list the server's prompts, call
Call [`ClientSession.Prompts`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientSession.Prompts) to get an iterator.
If needed, you can use the lower-level
[`ClientSession.ListPrompts`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientSession.ListPrompts) to list the server's prompts.
Call [`ClientSession.GetPrompt`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientSession.GetPrompt) to retrieve a prompt by name, providing
arguments for expansion.
Set [`ClientOptions.PromptListChangedHandler`](https://pkg.go.dev/github.com/modelcontextprotocol/go-sdk/mcp#ClientOptions.PromptListChangedHandler) to be notified of changes in the list of prompts.
%include ../../mcp/server_example_test.go prompts -
## Resources

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@ -0,0 +1,83 @@
// Copyright 2025 The Go MCP SDK Authors. All rights reserved.
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
package mcp_test
import (
"context"
"fmt"
"log"
"github.com/modelcontextprotocol/go-sdk/mcp"
)
// !+prompts
func Example_prompts() {
ctx := context.Background()
promptHandler := func(ctx context.Context, req *mcp.GetPromptRequest) (*mcp.GetPromptResult, error) {
return &mcp.GetPromptResult{
Description: "Hi prompt",
Messages: []*mcp.PromptMessage{
{
Role: "user",
Content: &mcp.TextContent{Text: "Say hi to " + req.Params.Arguments["name"]},
},
},
}, nil
}
// Create a server with a single prompt.
s := mcp.NewServer(&mcp.Implementation{Name: "server", Version: "v0.0.1"}, nil)
prompt := &mcp.Prompt{
Name: "greet",
Arguments: []*mcp.PromptArgument{
{
Name: "name",
Description: "the name of the person to greet",
Required: true,
},
},
}
s.AddPrompt(prompt, promptHandler)
// Create a client.
c := mcp.NewClient(&mcp.Implementation{Name: "client", Version: "v0.0.1"}, nil)
// Connect the server and client.
t1, t2 := mcp.NewInMemoryTransports()
if _, err := s.Connect(ctx, t1, nil); err != nil {
log.Fatal(err)
}
cs, err := c.Connect(ctx, t2, nil)
if err != nil {
log.Fatal(err)
}
// List the prompts.
for p, err := range cs.Prompts(ctx, nil) {
if err != nil {
log.Fatal(err)
}
fmt.Println(p.Name)
}
// Get the prompt.
res, err := cs.GetPrompt(ctx, &mcp.GetPromptParams{
Name: "greet",
Arguments: map[string]string{"name": "Pat"},
})
if err != nil {
log.Fatal(err)
}
for _, msg := range res.Messages {
fmt.Println(msg.Role, msg.Content.(*mcp.TextContent).Text)
}
// Output:
// greet
// user Say hi to Pat
}
// !-prompts