SEP-2166: Out-of-Band Resource Access via HTTPS URLs#2166
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abrookins wants to merge 2 commits intomodelcontextprotocol:mainfrom
Open
SEP-2166: Out-of-Band Resource Access via HTTPS URLs#2166abrookins wants to merge 2 commits intomodelcontextprotocol:mainfrom
abrookins wants to merge 2 commits intomodelcontextprotocol:mainfrom
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FYI @SamMorrowDrums since this touches on your past feedback. |
localden
changed the title
Proposes adding optional httpUrl and httpUrlExpiresAt fields to the Resource interface, enabling MCP servers to provide direct HTTPS access URLs alongside the canonical MCP resource URI. This allows resources to be accessed both through MCP (via resources/read) and directly via HTTPS by processes that may not have an authenticated MCP client connection, such as code executing in sandboxed environments.
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Proposes adding optional
httpUrlandhttpUrlExpiresAtfields to the Resource interface, enabling MCP servers to provide direct HTTPS access URLs alongside the canonical MCP resource URI.This allows resources to be accessed both through MCP (via
resources/read) and directly via HTTPS by processes that may not have an authenticated MCP client connection, such as code executing in sandboxed environments.Motivation and Context
Large tool outputs create context overhead when passed through LLM conversations. While Anthropic's "Code Execution with MCP" pattern allows agents to reduce this overhead by executing code that calls MCP tools directly, this requires the execution environment to have an authenticated MCP client connection, which sandboxes and subprocesses may lack.
This proposal enables servers to provide HTTPS URLs that any HTTP client can fetch, bridging the gap between MCP-connected contexts and disconnected execution environments.
Related discussions:
Resource.uriScopeto enable direct reads #607: Resource.uriScope (closed — needs SEP)How Has This Been Tested?
easy-mcp-proxy implements this pattern using a custom response format. The proxy caches large tool outputs, generates signed HTTPS URLs with expiration, and returns preview text plus retrieval URLs to clients. The pattern works well used with Claude Desktop (using the "All domains" allow list for sandbox access) and coding agents such as Augment Code. If this SEP is accepted, easy-mcp-proxy would be updated to use the standardized fields.
Breaking Changes
None. Both fields are optional additions to the existing
Resourceinterface.Types of changes
Checklist
AI Disclosure
This SEP was drafted with AI assistance (Augment Code). The problem definition, use cases, and technical approach were developed collaboratively with the author providing direction and review.