fix(deps): update module github.com/modelcontextprotocol/go-sdk to v1.6.1

[botty-mcbottington]

This PR contains the following updates:

Package	Change	Age	Confidence
github.com/modelcontextprotocol/go-sdk	v1.4.1 → v1.6.1

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Release Notes

modelcontextprotocol/go-sdk (github.com/modelcontextprotocol/go-sdk)

v1.6.1

Compare Source

This release adds an MCPGODEBUG flag to opt out of the Content-Type check on POST requests.

Behavior Changes

Prior to v1.6.0 (v1.4.0...v1.5.0), the Content-Type check on POST requests was gated by the same disablecrossoriginprotection MCPGODEBUG flag as the cross-origin protection. In v1.6.0, the cross-origin protection was disabled by default (replaced by the opt-in enableoriginverification flag), but the Content-Type check was kept on unconditionally, leaving no way to disable it.
This release restores an escape hatch for both the Streamable HTTP and SSE transports: setting MCPGODEBUG=disablecontenttypecheck=1 skips the Content-Type: application/json validation on POST requests.
See #​957.

What's Changed

• mcp: add MCPGPDEBUG for opt-in Content-Type check by @​guglielmo-san in #​972

Full Changelog: modelcontextprotocol/go-sdk@v1.6.0...v1.6.1

v1.6.0

Compare Source

This release is equivalent to v1.6.0-pre.1. Thank you to those who tested the pre-release.

In this release we introduce several smaller fixes and improvements, and we started working for release 2026-06-30. The main new feature is the introduction of ClientCredentialsHandler for OAuth client credentials grant.

Add ClientCredentialsHandler for OAuth client credentials grant

Added ClientCredentialsHandler implementing auth.OAuthHandler using the OAuth 2.0 Client Credentials grant (RFC 6749 Section 4.4) for service-to-service authentication with pre-registered credentials.

• extauth: add ClientCredentialsHandler for OAuth client credentials grant by @​ravyg in #​895

2026-06-30 Release related PRs

• feat: add automatic application_type inference by @​guglielmo-san in #​904

  New application_type field is added to the ClientRegistrationMetadata for DynamicClientRegistration. If not specified, the application_type will be inferred from the RedirectURIs. This implements SEP-837.

• feat: HTTP Header Standardization for method and name by @​guglielmo-san in #​907

  By mirroring key fields from the JSON-RPC payload into HTTP headers, network intermediaries such as load balancers, proxies, and observability tools can route and process MCP traffic without deep packet inspection, reducing latency and computational overhead. This partially implements SEP-2243.

Behavior Changes

SetError Behavior Change

Previously the SetError method on CallToolResult always overwrote the Content field with the error text. Now SetError preserves the existing value if it has already been populated. You can restore the previous behavior by setting the environment variable seterroroverwrite=1.

• mcp: preserve existing Content in SetError by @​ravyg in #​864

Cross-Origin Protection Default Change

Previously (v1.4.1-v1.5.0) default (zero-value) cross-origin protection was applied when CrossOriginProtection in StreamableHTTPOptions was nil. Now cross-origin protection is not enabled by default when CrossOriginProtection is nil.
You can restore the previous behavior (enable by default) by setting enableoriginverification=1.

• mcp: remove default cross origin protection by @​maciej-kisiel in #​906

disablecrossoriginprotection was replaced by enableoriginverification after the default was changed to not enable cross-origin protection.

jsonescaping option was removed, according to plan.

Other Changes to the SDK

• internal: remove unused util functions by @​alexandear in #​871
• build(deps): bump github/codeql-action from 4.32.4 to 4.35.1 by @​dependabot[bot] in #​873
• build(deps): bump actions/setup-go from 6.3.0 to 6.4.0 by @​dependabot[bot] in #​874
• build(deps): bump actions/setup-node from 6.2.0 to 6.3.0 by @​dependabot[bot] in #​875
• build(deps): bump dominikh/staticcheck-action from 1.4.0 to 1.4.1 by @​dependabot[bot] in #​872
• oauthex: accept 200 in client registration by @​MatyasVondraOutreach in #​877
• mcp: allow Content-Type parameters in streamable transport by @​rafaeljusto in #​878
• mcp: preserve existing Content in SetError by @​ravyg in #​864
• mcp: fix race condition in ServerSession.startKeepalive by @​begelundmuller in #​856
• chore: preserve CNAME when deploying to GitHub pages by @​maciej-kisiel in #​884
• extauth: refactor enterprise auth tests by @​maciej-kisiel in #​879
• feat: Add Support for mkdocs by @​Dinesht04 in #​883
• mcp: add DNS rebinding and cross origin protections to SSE transport by @​maciej-kisiel in #​891
• mcp: log out-of-band errors instead of dropping them by @​ravyg in #​887
• mcp: don't close session when keepalive ping returns method-not-found by @​maciej-kisiel in #​900
• mcp: accept parameterized Content-Type types by @​kalvinnchau in #​890
• mcp: remove default cross origin protection by @​maciej-kisiel in #​906
• Update README.md by @​N-Masi in #​896
• mcp: preserve transport errors in Write error chain by @​jpugliesi in #​888
• mcp: do not re-prompt OAuth after cancelled Authorize by @​ravyg in #​885
• mcp: Upgrade jsonschema-go by @​rafaeljusto in #​912
• internal/jsonrpc2: remove unused code by @​maciej-kisiel in #​910
• MCPGODEBUG update for 1.6.0 by @​maciej-kisiel in #​893

New Contributors

• @​MatyasVondraOutreach made their first contribution in #​877
• @​rafaeljusto made their first contribution in #​878
• @​begelundmuller made their first contribution in #​856
• @​Dinesht04 made their first contribution in #​883
• @​N-Masi made their first contribution in #​896
• @​jpugliesi made their first contribution in #​888
• @​guglielmo-san made their first contribution in #​904

Full Changelog: modelcontextprotocol/go-sdk@v1.5.0...v1.6.0-pre.1

v1.5.0

Compare Source

This release is equivalent to v1.5.0-pre.1. Thank you to those who tested the pre-release.

In this release we introduce important enhancements to the client-side OAuth flows. We also introduce several smaller fixes and improvements.

Stabilization of client-side OAuth APIs

As previously communicated, we're stabilizing the client-side OAuth APIs in v1.5.0. This means that the mcp_go_client_oauth build tag will no longer be required to compile the functionality and standard backward compatibility guarantees apply from now on.

Compared to the experimental support published in v1.4.0, we made some backwards incompatible changes:

• auth.AuthorizationCodeHandlerConfig.AuthorizationCodeFetcher's type was changed from func(context.Context, *auth.AuthorizationArgs) (*auth.AuthorizationResult, error) to auth.AuthorizationCodeFetcher which is a reusable definition carrying the same underlying function type.
• auth.AuthorizationCodeHandlerConfig.PreregisteredClientConfig was removed and replaced with auth.AuthorizationCodeHandlerConfig.PreregisteredClient which uses a newly introduced oauthex.ClientCredentials type. The type used previously (auth.PreregisteredClientConfig) has been removed.
• Deprecated functionality has been removed from both auth and oauthex packages.

• all: stabilize client OAuth support by @​maciej-kisiel in #​861

Enterprise Managed Authorization support added

Support for Enterprise Managed Authorization has been added to auth/extauth package. Huge thanks to @​radar07 for the implementation!

• Enterprise managed authorization by @​radar07 in #​770

Note: this support is part of an official MCP extension and is not part of the core protocol. The support of this functionality is not covered by the principles defined in SDK tiers.

Other changes to the SDK

• examples: fix OAuth client example after latest changes. by @​maciej-kisiel in #​820
• build(deps): bump actions/upload-artifact from 4.6.1 to 7.0.0 by @​dependabot[bot] in #​824
• build(deps): bump ossf/scorecard-action from 2.4.1 to 2.4.3 by @​dependabot[bot] in #​825
• build(deps): bump actions/setup-go from 6.2.0 to 6.3.0 by @​dependabot[bot] in #​827
• build(deps): bump actions/checkout from 4.2.2 to 6.0.2 by @​dependabot[bot] in #​826
• mcp: simplify and unify unit tests introduced for sampling with tools. by @​maciej-kisiel in #​799
• auth: fix 2025-03-26 backcompat by @​maciej-kisiel in #​821
• chore: update deps after v1.4.0 release by @​maciej-kisiel in #​829
• build(deps): bump github/codeql-action from 3 to 4 by @​dependabot[bot] in #​823
• mcp: update latestProtocolVersion to 2025-11-25 by @​findleyr in #​724
• mcp: protect ioConn.protocolVersion with a mutex by @​maciej-kisiel in #​832
• examples: add an example that display header forwarding. by @​maciej-kisiel in #​836
• internal: fix Unicode zero character handling by @​maciej-kisiel in #​841
• auth: allow passing custom http.Client to AuthorizationCodeHandler by @​maciej-kisiel in #​840
• mcp: verify 'Origin' and 'Content-Type' headers by @​maciej-kisiel in #​842
• auth: return scope in WWW-Authenticate header. by @​maciej-kisiel in #​834
• mcp: fix setProgressToken when Meta is nil by @​StevenRChen in #​846
• all: clean up Go 1.24 specific code. by @​maciej-kisiel in #​850
• mcp: re-enable race test after fixing data races by @​maciej-kisiel in #​851
• mcp: handle empty chunks in MemoryEventStore by @​jba in #​862
• oauthex: use internal JSON library for decoding. by @​maciej-kisiel in #​866
• all: fix typos by @​alexandear in #​869
• mcp: return input validation errors as tool results, not JSON-RPC errors by @​ravyg in #​863
• all: modernize code by @​alexandear in #​868
• mcp: accept parameterized Accept media types by @​kalvinnchau in #​853
• mcp: use http.ResponseController to ensure writes are flushed by @​toofishes in #​870

New Contributors

• @​StevenRChen made their first contribution in #​846
• @​radar07 made their first contribution in #​770
• @​alexandear made their first contribution in #​869
• @​ravyg made their first contribution in #​863
• @​kalvinnchau made their first contribution in #​853
• @​toofishes made their first contribution in #​870

Full Changelog: modelcontextprotocol/go-sdk@v1.4.1...v1.5.0

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 45.16%. Comparing base (74e0f03) to head (fa06ec9).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #296   +/-   ##
=======================================
  Coverage   45.16%   45.16%           
=======================================
  Files          53       53           
  Lines        4886     4886           
=======================================
  Hits         2207     2207           
  Misses       2523     2523           
  Partials      156      156           

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[botty-mcbottington]

ℹ️ Artifact update notice

File name: go.mod

In order to perform the update(s) described in the table above, Renovate ran the go get command, which resulted in the following additional change(s):

• 6 additional dependencies were updated

Details:

Package	Change
github.com/google/jsonschema-go	v0.4.2 -> v0.4.3
golang.org/x/mod	v0.32.0 -> v0.33.0
golang.org/x/net	v0.49.0 -> v0.50.0
golang.org/x/oauth2	v0.34.0 -> v0.35.0
golang.org/x/text	v0.33.0 -> v0.34.0
golang.org/x/tools	v0.41.0 -> v0.42.0

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