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
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Reviewed-by: Jonathan Amsterdam <jba@google.com>
Implementation of resources.
This follows the design sketched in design/design.md, except for
Server.FileResourceHandler, which will be in a forthcoming CL.
As the spec recommends, the server verifies an incoming URI from the
client against its list of resources, to make sure the URI came from one
of them.
Some things that aren't in the design doc:
- I provide an exported function that creates a "resource not found"
jsonrpc2.WireEror error for server authors to return.
A wrinkle: the MCP spec defines the error code for
"resource not found" as -32002 [1]. That code is reserved for use
by implementations of JSON-RPC, not applications. That matters to us
because our JSON-RPC implementation already uses that code for the
"server closing" error. I filed a bug against MCP about it [2] and
chose a different code for the "resource not found" error.
- As a slight convenience, I fill in some fields in the
ReadResourceResult if the handler doesn't set them.
[1] https://modelcontextprotocol.io/specification/2025-03-26/server/resources#error-handling
[2] https://github.com/modelcontextprotocol/modelcontextprotocol/issues/509
Change-Id: I06153da982ea00748a3691ded923448a880cea2a
Reviewed-on: https://go-review.googlesource.com/c/tools/+/671363
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Enhance the generator so that it recognizes initialisms like "Id" and
writes them in all caps, as is idiomatic for Go.
Also, fix the import path of jsonschema in the generated code.
Change-Id: Ib12e9fbd543d360035d5e324f0aefca584ac7c85
Reviewed-on: https://go-review.googlesource.com/c/tools/+/670916
Auto-Submit: Jonathan Amsterdam <jba@google.com>
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Reviewed-by: Robert Findley <rfindley@google.com>
Start writing up a formal design doc for an MCP SDK based on what we've
learned from the prototype. Include discussion of package layout,
jsonrpc2, and transport. Lay out the rest of the design sections,
leaving stub comments describing what they should cover.
Change-Id: Id0e5b408eac8c0acb5ef90a32d0d69473d8e83f0
Reviewed-on: https://go-review.googlesource.com/c/tools/+/670536
Reviewed-by: Jonathan Amsterdam <jba@google.com>
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Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
Auto-Submit: Robert Findley <rfindley@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
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Auto-Submit: Robert Findley <rfindley@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Pass the client Transport to NewClient instead of Connect.
Combine the ConnectionOptions with the ClientOptions.
Change-Id: I3acd6cf6d5bf46666742f2a73e2acaef2057ea77
Reviewed-on: https://go-review.googlesource.com/c/tools/+/670215
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>
The generated protocol package is part of the SDK API, so it shouldn't
be internal.
Change-Id: I5306af48019b1599707b939b348eb6ae4f766ca9
Reviewed-on: https://go-review.googlesource.com/c/tools/+/670356
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Reviewed-by: Jonathan Amsterdam <jba@google.com>
Remove ServerConnection.
- It's not in typescript or mcpgo APIs.
- Amortizing a client over multiple servers doesn't have any value.
Change-Id: I725b42569733d6836864d96b16898a10ae91e570
Reviewed-on: https://go-review.googlesource.com/c/tools/+/669575
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Add a missing CommandTransport that communicates with a sidecar process
over newline-delimited stdin/stdout, the counterpart to the existing
StdIOTransport.
Add a test using the usual TestMain trick.
Change-Id: I170ba78faf6b6d7fca7da1af11bf92e919b11ed5
Reviewed-on: https://go-review.googlesource.com/c/tools/+/668895
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Reviewed-by: Jonathan Amsterdam <jba@google.com>
Export the Transport interface, as there's no reason users shouldn't be
able to define their own transports: they are just bidirectional
streams.
Also, add a godoc example for basic Server usage.
Finally, remove some TODOs that existed due to a bad merge: they are
related to the (as yet unsubmitted) streamable HTTP transport.
Change-Id: Id669793fc80630e667d50611fe2876d09125a025
Reviewed-on: https://go-review.googlesource.com/c/tools/+/668675
TryBot-Bypass: Robert Findley <rfindley@google.com>
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
Auto-Submit: Robert Findley <rfindley@google.com>
Use the existing jsonrpc2 preemption mechanism to implement MCP
cancellation.
This was mostly straightforward, except where I got confused about ID
unmarshaling. Leave a note about using omitempty when it is available.
Change-Id: I13e073f08c5d5c2cc78d882da4e6ff47f09fb340
Reviewed-on: https://go-review.googlesource.com/c/tools/+/667578
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Reviewed-by: Jonathan Amsterdam <jba@google.com>
Add support for SSE transport, as defined by version 2024-11-05 and
2025-03-26 of the MCP spec.
In order to achieve this, the jsonrpc2 stream must be abstracted so that
we can implement it across multiple HTTP requests. This required some
refactoring of the jsonrpc2_v2 package, so that we can avoid the
Dialer/Binder interfaces and construct the Connection directly from its
constituent primitives.
Change-Id: Id627b5b5a474d92f2c613cfad904d14611e7c768
Reviewed-on: https://go-review.googlesource.com/c/tools/+/667475
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
Update the jsonrpc2 MCP framer to support both incoming and outgoing
batches. In order to achieve this, we must correlate the framed Reader
and Writer, which is not explicitly supported by the jsonrpc2 API, but
does work. A note is left to revisit the Framer interface.
Change-Id: If060cb5822da067833db20d58f5f112a0528da91
Reviewed-on: https://go-review.googlesource.com/c/tools/+/667295
Reviewed-by: Jonathan Amsterdam <jba@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
This CL contains an minimal prototype of an MCP SDK, using the
"new" jsonrpc2_v2 package (similar to x/exp/jsonrpc2).
Much is still yet to do, but this initial version addressed the
following aspects:
- Support for newline delimited JSONRPC2 framing, and message logging.
- A generated protocol package, containing type definitions to be used
in transport.
- A minimal jsonschema package to be used for both reading the MCP spec,
and for serving Tool input schemas.
- A transport abstraction, and two transport implementations: stdio, and
local (for testing).
- Client and Server types, to be configured with features and then
connected using their Connect methods, which return (respectively) a
ServerConnection and ClientConnection object.
- A minimal binding API for tools.
A catalog of things not yet done is in doc.go, but we should review this
CL eagerly, as it contains the fundamental building blocks of an
eventual SDK.
It is the intention that this package is more-or-less standalone, as it
may eventually be carved out into a separate repository. As such, its
only dependency within x/tools is jsonrpc2_v2, and the only change
required to that package is to expose a callback when the connection is
closed.
Change-Id: Ib66018961014f85a8884d56ab721d5642c98443c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/667036
Reviewed-by: Jonathan Amsterdam <jba@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
