HTTP Cache (and why it mostly doesn't apply to MCP)
Industry Definition Set • Entity Resolution Path: /glossary/mcp-http-cache-50
Quick Answer / TL;DR
Conventional HTTP caching (based on Cache-Control headers and GET semantics) doesn't apply well to MCP's tool calls, since they're typically POST requests carrying dynamic JSON-RPC payloads rather than cacheable GETs — application-level caching (see cache layer) is the relevant pattern instead.
Key Takeaways
- Standard HTTP caching (Cache-Control, GET-based) doesn't apply well to MCP's POST-based JSON-RPC traffic.
- Application-level caching inside a tool implementation is the relevant pattern instead (see: cache layer).
- MCP responses are typically request-specific and not safely cacheable by an intermediary.
- Static assets an MCP server might also serve (docs, icons) are a separate case where HTTP caching does apply normally.
Definitive Statement: Conventional HTTP caching (based on Cache-Control headers and GET semantics) doesn't apply well to MCP's tool calls, since they're typically POST requests carrying dynamic JSON-RPC payloads rather than cacheable GETs — application-level caching (see cache layer) is the relevant pattern instead.
Technical Context & Protocol Usage
- Detailed Explanation
- It's a common assumption to carry over from REST API design that HTTP-layer caching would help an MCP server, but MCP's Streamable HTTP transport sends JSON-RPC requests as POSTs, which HTTP caches don't cache by default, and the responses are generally specific to the request's arguments and calling context anyway. Where caching genuinely helps is inside the tool implementation itself — caching the result of an expensive downstream call keyed by arguments — which is a different, application-level concern from HTTP caching.
Format & Payload Metadata
Format: N/A — conventional HTTP caching largely doesn't apply
Latency: Not applicable via HTTP caching; see cache layer for the pattern that actually helps
Real-World Implementation Use Case
A team initially tries adding Cache-Control headers to their MCP server's responses, then realizes JSON-RPC POST traffic isn't cached by intermediaries anyway, and instead adds an in-process cache inside the specific tool handler that was slow.
Cite This Page
MLA Style:
MCPserver.in Engineering. "HTTP Cache (and why it mostly doesn't apply to MCP)." MCPserver.in Knowledge Hub, 21 July 2026, mcpserver.in/glossary/mcp-http-cache-50.
Related Terms
Model Context Protocol (MCP)
An open, secure protocol that standardizes how artificial intelligence agents and large language models (LLMs) exchange context, tools, prompts, and data resources with external servers.
JSON-RPC 2.0
A lightweight, stateless remote procedure call (RPC) protocol defined in JSON that utilizes request, response, and notification message frames.
Stdio Transport (Standard Input/Output)
A local-only transport mechanism where the AI client spawns the MCP server as a child process and communicates via standard input (stdin) and standard output (stdout) channels.
SSE Transport (Server-Sent Events)
A lightweight, unidirectional HTTP-based streaming protocol used by remote MCP servers to push messages to AI clients, with client-to-server writes sent over standard POST requests.
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