Expose the jsonrpc.Error type to allow access to underlying JSON-RPC
error codes. Also, expose common JSON-RPC error codes in the jsonrpc
package, and MCP error codes in the mcp package.
Also, implement support for the MCP URL elicitation required error
(-32042), enabling servers to request out-of-band user authorization and
clients to automatically handle these requests with retry logic.
Server-side:
- Add CodeURLElicitationRequired constant
- Add URLElicitationRequiredError() constructor.
Client-side:
- Add urlElicitationMiddleware to intercept URLElicitationRequired
errors and retry calls.
- Update callElicitationCompleteHandler to signal waiting operations.
- Fix capability advertisement to support both form and URL modes.
Fixes#452Fixes#623
Implement SEP 986, enforcing restrictions on tool names. Since we're
already at v1 we couldn't turn this into a panic, so use an error log
instead. This is consistent with the typescript SDK. A note is left in
our 'rough edges' doc to panic in v2.
Fixes#621
Our validation logic was avoiding double-unmarshalling as much as
possible, by parsing before validation and validating the Go type.
This only works if the Go type has the same structure as its JSON
representation, which may not be the case in the presence of types with
custom MarshalJSON or UnmarshalJSON methods (such as time.Time).
But even if the Go type doesn't use any custom marshalling, validation
is broken, because we can't differentiate zero values from missing
values.
Bite the bullet and use double-unmarshalling for both input and output
schemas. Coincidentally, this fixes three bugs:
- We were accepting case-insensitive JSON keys, since we parsed first,
even though they should have been rejected. A number of tests were
wrong.
- Defaults were overriding present-yet-zero values, as noted in an
incorrect test case.
- When "arguments" was missing, validation wasn't performed, no defaults
were applied, and unmarshalling failed even if all properties were
optional.
First unmarshalling to map[string]any allows us to fix all these bugs.
Unfortunately, it means a 3x increase in the number of reflection
operations (we need to unmarshal, apply defaults and validate,
re-marshal with the defaults, and then unmarshal into the Go type).
However, this is not likely to be a significant overhead, and we can
always optimize in the future.
Update github.com/google/jsonschema-go to pick up necessary improvements
supporting this change.
Additionally, fix the error codes for invalid tool parameters, to be
consistent with other SDKs (Invalid Params: -32602).
Fixes#447Fixes#449
Updates #450
Replace all occurrences of ServerRequest[*CallToolParams] and other
concrete instantiations with CallToolRequest and the like.
Make the XXXRequest types aliases, to preserve the convenience of
generics for the internal machinery (see shared.go, for example.)
I will expand the aliases in a followup PR.
Change 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
- Fix tool error handling to properly distinguish between protocol
errors and tool execution errors
- Return structured JSON-RPC errors directly for protocol-level issues
- Embed regular tool errors in CallToolResult as per MCP specification
- Improve server error responses for unknown prompts and tools
- Add comprehensive tests for both structured and regular error handling
Handlers and client/server methods take a single request argument
combining the session and params. This slightly simplifies the signature
for handlers, since there is no longer an often-ignored session
argument.
But more importantly, it opens the door to adding more information in
requests, such as auth info and HTTP request headers.
For #243.
BREAKING CHANGE
Change the API for adding tools, prompts, resources and resource
templates to a server.
The ServerXXX types are gone along with the plural Add methods
(AddTools, AddPrompts etc.)
Instead there are single Add methods (AddTool, AddPrompt).
In addition, instead of NewServerTool, there is AddTool[In, Out].
Fixes#73.
The NewTool and NewPrompt constructors were unidiomatic, because they
returned a ServerTool and ServerPrompt, respectively, rather than a Tool
and Prompt. Rename to be consistent with the constructed object name.
Change-Id: Ife3f16f783368401f792660c4272e1bb5ae61638
Reviewed-on: https://go-review.googlesource.com/c/tools/+/682375
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Before validating a tool input, apply the defaults from the input
schema.
Change-Id: I23fae4087f898d51b3d1f0578d3203b954cb5f2d
Reviewed-on: https://go-review.googlesource.com/c/tools/+/680395
Reviewed-by: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
CallToolParams.Arguments is any.
Clients can send whatever they want.
Tool authors who create their own ToolHandler (bypassing NewTool)
will receive the arguments as a map[string]any which has been
validated against the input schema.
Tool authors who call NewTool can choose the type that the arguments
unmarshal into.
There is no double-unmarshaling and no downcasting.
There is no way for tool authors to avoid the unmarshal, and no way to
avoid the validation unless the omit an input schema, which is probably
bad for LLMs. If tool authors want this optimization, we can provide
it later.
Change-Id: Ieb201e56c7fb8a23bb1a93b27e946630ec9e79ad
Reviewed-on: https://go-review.googlesource.com/c/tools/+/679595
TryBot-Bypass: Jonathan Amsterdam <jba@google.com>
Auto-Submit: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
A tool now validates its input with its InputSchema.
Change schema inference to allow explicit nulls for fields of
pointer type.
We assume the schema has no external references. For example, the
following schema cannot be handled:
{
"$ref": "https://example.com/other.json"
}
Schemas with internal references, like to a "$defs", are fine.
Change-Id: I6ee7c18c2c5cb609df0b22a66da986f7ea64bbe4
Reviewed-on: https://go-review.googlesource.com/c/tools/+/670676
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Make Tool APIs future-proof by pushing generics into CallToolParams, and
using CallToolParams throughout. This has several advantages:
- We no longer need the awkward CallToolOptions type, which is almost
but not quite like CallToolParams.
- NewTool no longer needs to define its own handler type: it accepts a
ToolHandler[TArgs]. This also means its signature is future-proof.
Additionally, provide a `CallTool` helper (the analog of NewTool) to
serve as a more strongly typed variant of `ClientSession.CallTool`.
+ design, protocol generation
Change-Id: I80172a25bc50734dae84a541aa4776ed9161694e
Reviewed-on: https://go-review.googlesource.com/c/tools/+/676495
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Auto-Submit: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Do a pass through the design doc, adding a bit more clean-up and
commentary.
Additionally, update ServerTool and ServerPrompt to be consistent with
the design.
Change-Id: I1b75c4690d86fe8946d512cb36a1fc2938b3c883
Reviewed-on: https://go-review.googlesource.com/c/tools/+/672576
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
Auto-Submit: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Bring the Server implementation up to date with the spec by renaming
ServerConnection to ServerSession. Also update variable names, which
were in various states of disarray from the multiple renamings of this
type.
Change-Id: I4aec883db6d0500fb91e6daa51b702614877cf8a
Reviewed-on: https://go-review.googlesource.com/c/tools/+/672655
Auto-Submit: Robert Findley <rfindley@google.com>
TryBot-Bypass: Robert Findley <rfindley@google.com>
Commit-Queue: Robert Findley <rfindley@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Use pointers for the protocol's struct types, to future-proof against
them getting large.
Change-Id: I55b204080a41c8140539697ba264e502e912e613
Reviewed-on: https://go-review.googlesource.com/c/tools/+/672575
Reviewed-by: Robert Findley <rfindley@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
In accordance with the updated design, merge the protocol package into
the mcp package. To do so, rename protocol.Content to WireContent and
protocol.ResourceContents to WireResource.
Also, remove some stray logging in readResource.
Change-Id: I76f61ce8d67dd3ac520ef2e1959ade0a0785a480
Reviewed-on: https://go-review.googlesource.com/c/tools/+/672375
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
It's too confusing that you send server requests through the Client, and
send client requests through the ClientConnection. Rename
ClientConnection to ServerConnection, so that the types on the
server side of the control diagram start with 'Server'.
Change-Id: Idfd27af464a9296a2341cd23b2075cd9d0eb6b45
Reviewed-on: https://go-review.googlesource.com/c/tools/+/670538
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Robert Findley <rfindley@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
The jsonschema package is part of of the API of the mcp package,
so it should not be internal.
Change-Id: I9520797837329fc2cda09c2f46ec4d48d031b9d3
Reviewed-on: https://go-review.googlesource.com/c/tools/+/669996
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>
This is the first CL that deals with the process of preparing a schema for validation.
Perform some basic checks on the scheme. Along the way, compile regexps and store
them in the schema for use during validation.
Change-Id: I0e5e6ce28656dcecb6d2d4b2fdc98998fa05b6f1
Reviewed-on: https://go-review.googlesource.com/c/tools/+/669696
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Alan Donovan <adonovan@google.com>
Add support for 'prompts/list' and 'prompts/get', and registering
prompts on the server using AddPrompts. Add a 'MakePrompt' helper to
construct prompts from a prompt handler using reflection.
Change-Id: I479cb9c9b99313cca99640c1f5ea1939363759e6
Reviewed-on: https://go-review.googlesource.com/c/tools/+/669015
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Implement variadic options for building tools and schemas, to allow
easier customization of tool input schemas.
Also, make fields required, unless they are marked as "omitempty".
Change-Id: I7a29258fae3ec5e7ea4906ed30ed6750979de962
Reviewed-on: https://go-review.googlesource.com/c/tools/+/668955
Reviewed-by: Jonathan Amsterdam <jba@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
