standard
JSON-RPC is a lightweight, stateless RPC protocol that encodes method calls and responses as JSON; version 2.0 underlies many APIs, including MCP.
No evidence-backed relationships are recorded.
A four-container demo runs one Deadbugz-shaped MCP server behind two brokers. Only the broker that hashes name, description and inputSchema on the first tools/list refused the swap that lands after three tool calls.
Reality
An AWS waste scanner now exposes five read-only MCP tools that hand back totals, counts and breakdowns its engine computed. The findings themselves stay in a report file on disk, so the model has nothing to sum.
Reality
A consultancy's account of production MCP work on Django client apps calls the protocol a transport layer. Its sample server calls django.setup(), imports the Order model, and dispatches tool calls on a string.
Reality
The author of laravel-rest pointed one Eloquent-style client at 62 public APIs across 470 unmocked scenarios and published the wire logs for three of them. Where the rows and the page total live is declared per API.
Reality
Codex made the session Item a wire type and Pi gave every entry a nullable parentId, while Claude Code squeezes the transcript in five stages. The three designs diverge on what stays addressable after compaction.
Reality
PolicyAware 0.4.4 evaluates identity, tenant, region, arguments and risk tier before an agent's action changes state. Enforcement sits inline on every turn, and the project's own guidance is that adopters measure what that costs.
Reality
Version 1.133 runs agents in a standalone host that survives window closes and can be reached over SSH, and the session protocol is now an MIT-licensed spec.
Reality
A fault-injection scan of 31 popular MCP servers found only 3% of their 265 tools declare an output contract that would reject a well-typed but wrong response. The failing 97% split into two different problems.
Reality
A developer logged every byte his own Apify Actor sent back over raw JSON-RPC. The agent receives 9,135 characters of schema, 23 properties deep, with the Console form's emoji intact and nothing marked required.
Reality
The per-session spawn is what stdio means, so the fix is one loopback daemon per machine. That same consolidation makes a single restart blind every open session, which is where the design work went.
Reality
Agent tool calls look like ordinary HTTPS, so Cloudflare's new controls match on protocol headers rather than on destinations. They only see traffic you already decrypt, which is where the adoption cost sits.
Reality
In the final 2026-07-28 MCP spec, an empty nextCursor means keep going. A falsy check ends the loop instead, and the call still returns success.
Reality
A 1,180-record knowledge base serves crawlers and agents from the same 0.39-second build. The MCP endpoint imports what the build wrote, because two derivations of one join eventually disagree.
Reality
A developer's four-tool server read as empty on glama, Smithery and mcp.directory, because tools/list arrives without a token. The fix is a four-method allowlist.
Reality
A dev.to writeup makes the structural case: tool and schema drift exists only as a diff between two snapshots, so no single health probe can find it, however thorough.
Reality
CircleCI's explainer puts MCP in front of the APIs you already run. The integration work is small; deciding which operations become agent-legible capabilities is not.
Reality
HTTP+SSE, the two-endpoint transport from the 2024-11-05 revision, is deprecated and eligible for removal. Tutorials ranking today still teach it.
Reality
A dev.to walkthrough on agentgateway makes a narrow point worth taking seriously: an agent that retries on failure will keep hitting an unrated MCP server until something gives.
Reality