Summary

This SEP proposes resources/create and resources/delete — making the MCP resources interface bidirectional. The current spec is read-only from the client's perspective. This proposal adds a standard way for clients to submit resources to a server and receive a URI back.

Motivation

Multi-agent and job orchestration systems repeatedly build the same pattern with custom tools: submit a payload (prompt, config, data), get a reference back, use that reference later when the job runs. Standardizing this as resources/create makes it composable across any compliant client and server.

Concrete use cases covered in the SEP:

• Job orchestration: storing prompt templates and configs server-side before a job executes
• Agent handoff: Agent A deposits content for Agent B via a shared server
• Async pipelines: a client pre-loads context a long-running job will need after the client disconnects

What's in the SEP

• resources/create — submit content, receive a stable URI
• resources/delete — cleanup, scoped to resources the client created
• Capability negotiation via capabilities.resources.create/delete
• Binary content via base64 (consistent with BlobResourceContents)
• Open metadata field for hints (TTL, tags) with ignore-unknown semantics
• Security considerations: storage limits, access control, content injection, deletion scope
• Three open questions for community input

Closes

Supersedes issue #2570 (submitted incorrectly as an issue rather than a PR — apologies for the noise).