This CL implements a completion handler for the server and a complete
method for the client.
Fixes: #12
<!-- Provide a brief summary of your changes -->
## Motivation and Context
<!-- Why is this change needed? What problem does it solve? -->
This adds support for completion.
## How Has This Been Tested?
<!-- Have you tested this in a real application? Which scenarios were
tested? -->
Added tests and an example.
## Breaking Changes
<!-- Will users need to update their code or configurations? -->
N/A
## Types of changes
<!-- What types of changes does your code introduce? Put an `x` in all
the boxes that apply: -->
- [ ] Bug fix (non-breaking change which fixes an issue)
- [x] New feature (non-breaking change which adds functionality)
- [ ] Breaking change (fix or feature that would cause existing
functionality to change)
- [ ] Documentation update
## Checklist
<!-- Go over all the following points, and put an `x` in all the boxes
that apply. -->
- [x] I have read the [MCP
Documentation](https://modelcontextprotocol.io)
- [x] My code follows the repository's style guidelines
- [x] New and existing tests pass locally
- [x] I have added appropriate error handling
- [x] I have added or updated documentation as needed
## Additional context
<!-- Add any other context, implementation notes, or design decisions
-->
After some experience with the flattened version of Content, we see that
it can easily lead to incorrect usage and is a harder API to read.
Therefore, this CL changes back to a design similar to what we had prior
to https://go.dev/cl/672415, though opting to promote content
unmarshalling to the protocol types that use it, which leads to an
overall simpler api.
* mcp: move to 2025-06-18 schema
Add types and fields for the latest MCP schema.
The main challenge here was dealing with the presence of _meta fields
on many types, like Tool, Prompt and Resource.
- Distinguish between the _meta field of a request's params, which
includes a progress token, from the _meta field on other types,
which is simply a map.
- Redefine GetMeta to return a pointer to the map. We wanted to avoid
that, but I don't see a clean way to do so. An alternative would be
to have GetMeta return a map, and SetMeta to set it.
- Provide GetProgressToken for requests only (not notifications or other
types).
- Still to do: deal with the meta and annotation fields of ContentBlock,
which are currently duplicated for Resource and ResourceContents.
* Meta and progress token redesign
This CL adds a NotifyProgress function and a ProgressNotificationHandler
to enable progress sending and handling.
Subsequent CL's to follow to handle progress updates for other methods such as list or readresource.
Change-Id: Ifcc422e6f6231d7d773d5432c1cf64032d796709
Reviewed-on: https://go-review.googlesource.com/c/tools/+/681116
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
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Auto-Submit: Sam Thanawalla <samthanawalla@google.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>
Provide support for resource templates on the client and server.
Adding, removing and listing resource templates looks just like those
operations on resources.
Although the spec provides no guidance on the unique ID for resource
templates, we follow most existing SDKs, as well as the parallel with
resources, and index on the URI template rather than the name.
As the spec recommends, the server verifies an incoming URI in a
ReadResource request against its list of resources and resource
templates, to make sure the URI came from one of them. The main
technical challenge here is the need to check that a URI template could
have produced a particular URI.
I wrote a very simplified version of this check. At some point
we should switch to github.com/yosida95/uritemplate/v3.
Change-Id: I1e34dd01c8f2171123c68c045ad62f5e85c05e7c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/680158
Auto-Submit: Jonathan Amsterdam <jba@google.com>
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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>
This CL streamlines the client side pagination logic by adding a generic
helper that handles pagination. This also simplifies the existing tools
iterator method.
Change-Id: If4304deda1ccd22d0c4580d76deaefc64e5dfeb9
Reviewed-on: https://go-review.googlesource.com/c/tools/+/676975
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Reviewed-by: Robert Findley <rfindley@google.com>
Auto-Submit: Sam Thanawalla <samthanawalla@google.com>
Reviewed-by: Jonathan Amsterdam <jba@google.com>
This uncovered a problem in how we represent resource results:
contents is a slice, not a single value.
I tried to use a file resource, but the server->client ListRoots
call didn't work because synthetic responses aren't supported.
Left a TODO.
I enhanced the hello example so I that could use the MCP Inspector to
work with resources.
The falseSchema change fixes a potential bug where schemas are
re-used, which is disallowed.
Change-Id: I1f0198043cb6221c2a03f4f83aa0bafbc71167f4
Reviewed-on: https://go-review.googlesource.com/c/tools/+/677136
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Auto-Submit: Jonathan Amsterdam <jba@google.com>
Meta is a struct that contains a map[string]any, and a ProgressToken
field.
Each Params and Result type has a Meta as a value field.
Meta marshals and unmarshals specially, so the ProgressToken field
becomes part of the map. The marshalling code is generalized in
anticipation of every Params and Result growing a map of additional
properties.
Change-Id: I6d2f34270d33501c96437f24f91ef3e51d20d955
Reviewed-on: https://go-review.googlesource.com/c/tools/+/674956
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
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Auto-Submit: Jonathan Amsterdam <jba@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Provide a ServerSession method that directly implements the spec
method.
Also provide a custom slog.Handler that writes a notification on each
log call. It uses a slog.JSONHandler to format the message as JSON, then
adds the additional fields of LoggingMessageParams.
I decided that the direct method should handle levels, since that is
in the spec, but that rate-limiting is an extra feature, so is only
provided in the slog handler.
Change-Id: I1190ca124e992e61fb633ac52ee3492c8e6d99c9
Reviewed-on: https://go-review.googlesource.com/c/tools/+/674498
Auto-Submit: Jonathan Amsterdam <jba@google.com>
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Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Add notification logic for intialization and list changes.
Change-Id: I1d392bb49d5995f2046c400da955a033ab2715ce
Reviewed-on: https://go-review.googlesource.com/c/tools/+/673775
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
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Augment the generator to create constants for all method names.
Change-Id: I858e516b1afec0aa3cf3b9852cbdfc16aec4c553
Reviewed-on: https://go-review.googlesource.com/c/tools/+/673177
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
Implement the dispatcher middleware framework, allowing users to
wrap method dispatching with their own code.
The Dispatcher functions have an untyped params arg, but expect its
value to be a typed, unmarshaled XXXParams struct. That required
splitting the elegant dispatch[P, R] function into two parts, one
to do the unmarshaling and one to call the method. The nicest way
I could find to do that was to map from method names to a pair
of functions, one to unmarshal and one to call. We could also write
it as two switches on method name, which would require less machinery
but would duplicate the list of method names, already a tad fragile
because they are literal strings.
I also exported the initialize params and result, so user Dispatchers
could access them. All Params and Result types will have to be exported
for that reason.
Change-Id: Ie2c95cc17b4ef3d3d095dccdadb294e5f1590796
Reviewed-on: https://go-review.googlesource.com/c/tools/+/673515
Reviewed-by: Robert Findley <rfindley@google.com>
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Since cancellation is handled transparently, this type need not be
exported.
Change-Id: Id4e195b0c3bd49eca52587032a027ffa449eb9d1
Reviewed-on: https://go-review.googlesource.com/c/tools/+/672796
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Reviewed-by: Sam Thanawalla <samthanawalla@google.com>
Change the type of CallToolParams.Arguments to json.RawMessage.
Change-Id: Ief16ef261b9f41566a1a16efc60a9382a8d414eb
Reviewed-on: https://go-review.googlesource.com/c/tools/+/672615
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Reviewed-by: Robert Findley <rfindley@google.com>
To ensure backward compatibility, every method in the spec now takes a
*Params struct and returns a *Result struct.
CallTools is an exception: we'll change that in the next CL.
Change-Id: I58835239c67582401b8c9c2d070702d270131c08
Reviewed-on: https://go-review.googlesource.com/c/tools/+/672595
Reviewed-by: Robert Findley <rfindley@google.com>
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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>
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Now that the protocol package is merged into the mcp package, clean up
the higher level 'Content' union types, in favor of types constructors.
Change-Id: I37bedb0ff0a296eef799ba65c37ca7f94ee1dbbe
Reviewed-on: https://go-review.googlesource.com/c/tools/+/672415
Reviewed-by: Jonathan Amsterdam <jba@google.com>
TryBot-Bypass: Jonathan Amsterdam <jba@google.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
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