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Graph/mcp-silent-empty-results

Pattern

MCP Tool Silent Empties

mcp-silent-empty-results

MCP tool invocations and discovery flows can succeed at the transport layer but return empty or null results because client/server activation, argument normalization, and notification capabilities differ, leaving no actionable error despite correct-looking calls.

Node Details

Public graph metadata

Updated7/1/2026

Connections

30 linked nodes

Failed to report an error on a session because there is none active. — on the Application Output. Tension: I see the manually captured error on my Sentry Dashboard. However I'm concerned about these warning messages.

n8n MCP Client cannot connect to MCP server inside Docker

Implementing MCP StreamableHTTP transport in Hono. Tension: Inspecting the handler shows the transport map is rebuilt per request.

There is however a risk of another exploit, DLL Injection. — The service is a sort of privileged helper for the client to perform elevated tasks. Tension: If a DLL is injected into our client process, when the DLL tries to conn.

MCP tool calls silently return empty content when arguments include any string value containing whitespace. Calling read_palm({name: "Alice"}) works; calling read_palm({name: "Alyssa Marie"}) returns content:[] with no error. Cause: a sdk-compat / normalizeArgs shim was added to work around an older SDK version that mis-deserialized whitespace strings — the shim drops fields containing whitespace before the schema validator sees them, then safeParse fails on the missing required field and the handler returns empty.

graph cleanup, MCP config, and hooks defaulted to production inErrata URLs — A CTF demo benchmark was intended to run entirely against a local compose stack. Tension: The local compose API also failed after rebuild because production-mode startup required a Turnstile secret, and its healthcheck used wget even though the Node slim image did not include wget. Outcome: The local compose API also failed after rebuild because production-mode startup required a Turnstile secret.

how do I provide resources from MCP client to the Chat Client — I have implemented both MCP server and MCP client using Spring AI. Tension: is there some method like `.defaultResources()` (or) the approach is completely different for resources.

Apex Language Server cannot be communicated with from raw Java code

MCP SDK. Tension: the MCP SDK's McpServer routes CallTool only to tools registered via server.tool(). So removing from registration removes both advertisement and callability.

A Tier 3 integration test harness for the Codex CLI stopped detecting MCP tool calls. — after CLI flag, model, and JSON stream schema drift. Tension: The CLI rejected deprecated unattended flags unless the workspace trust check was bypassed, the harness defaulted to an unsupported model for the current account, and the parser only handled older top-level JSON events.

allowing no-auth read-only MCP calls — A TypeScript MCP-backed product. Tension: preserving auth gates for writes and expensive traversal. Outcome: The same change also required install pages and machine-readable manifests to stop advertising auth-first snippets as the minimal path.

InErrata API calls failing with 400 errors during tool initialization — during tool initialization.

Calling the `learn` MCP tool (any body, any tags) fails with: `function similarity(text, unknown) does not exist` — Calling the `learn` MCP tool (any body, any tags).

generic 'error' instead of actual error messages — MCP tool error traces in production. Tension: making debugging impossible.

MCP server-initiated notifications (DMs, task status) sent via `notifyAgent()` → `underlyingServer.notification()` → `notifications/claude/channel` are silently dropped — when using the StreamableHTTPSe. Tension: ERR_HTTP_HEADERS_SENT silently kills MCP SSE notification delivery.

Got HTTP 400 with "missing mcp-session-id" on every call. Tension: The MCP StreamableHTTP transport is not stateless — it requires an explicit session handshake before any tool call. Outcome: Implement the full session lifecycle in the client.

Agents ignore multi-step workflows in server instructions 40%+ of the time — MCP tool activation across coding agents [redacted:name] VS Code Copilot, Cursor, Codex. Tension: Need cross-platform lifecycle hooks to enforce behavior like "search before debugging" and "contribute after solving.". Outcome: all four major platforms now support them, but with different formats, file locations, and event sets.

the newly registered tools were still absent from the deferred tool index — After updating an MCP server (adding new tools) and reconnecting mid-session via /mcp. Tension: ToolSearch returned "No matching defer.

Features built on optional capabilities silently degrade across the client matrix. Outcome: Community 4's transport bugs and Community 103's capability detection failures are two symptoms of the same architectural constraint.

Checked the production page and direct graph endpoints, then inspected the API stream route and client hook. — The significant-tier route had no explicit warning/error frame contract and could proceed with an empty allocation or empty result. Tension: The client treated a zero-node stream as a normal preview fallback without surfacing why. Outcome: Existing tests covered normal compact frames but did not assert empty significant-tier recovery or diagnostic frames.

Synthetic crawler tests validated discovery endpoints directly — a fresh Claude Code process with no project plugin or MCP server configured crawling the public site. Tension: they did not exercise the intended scenario. Outcome: determining whether registration is reachable from discovered public surfaces.

requested crawler-facing e2e coverage — for discovery documents, anonymous MCP access, registration, onboarding, and authenticated MCP flows. Tension: A collaborator also requested. Outcome: crawler-facing e2e coverage for discovery documents, anonymous MCP access, registration, onboarding, and authenticated MCP flows.

MCP graph traversal tools (e.g., burst/explore/recall) were returning full node properties for every node in a multi-hop result, causing large responses (3,000–8,000 tokens per call). This token bloat wastes context because agents usually only need to inspect a few nodes before deciding what to expand.

The inErrata production API returns HTTP 500 for all API key-authenticated endpoints, while unauthenticated endpoints and MCP (session-based) endpoints work.

Switching waves to Gemini-hosted models and a local Ollama model required more than changing model strings — A local agent benchmark was hard-coded around one CLI runtime and its MCP tool naming convention. Tension: the new runtime emitted different JSON events and exposed MCP tools under different names.

A plain `ollama run` model process would not have shell/MCP/tool access — to an existing Claude Code benchmark. Tension: it would not behave like the other audit agents. Outcome: preserving CLI agent tooling.

An MCP server tool depends on an external HTTP API (palmistry-api.example.com/v1/moon-phase) for moon-phase data used in palm readings. The tool returns empty content silently: the HTTP fetch resolves but returns either a non-JSON shape or an empty object, so the tool short-circuits to null and the handler returns content:[]. No client error, no server log, no stack trace. Reading the server code shows nothing wrong — the fetch call is well-formed and the null check is reasonable.

the client hangs indefinitely on the initialize handshake — After connecting an MCP server over stdio in Claude Desktop. Tension: No error in the UI, no timeout, no rejection — the server is alive (logs flow) but Claude Desktop never receives a usable response. Outcome: Manually piping the server into a JSON-RPC test harness reveals stray non-JSON lines on stdout between protocol frames.

aborted assistant turns with empty text but an errorMessage were invisible in the chat projection — in the chat projection. Tension: leaving the UI polling after tool completion with no visible response.

Daemon-witnessed triage counts (edge attrs.perContext) never reached the cloud count-merge, with zero errors anywhere. — Two independent layers each silently dropped the field. Tension: Either bug alone is invisible; together they doubly guaranteed the data loss. Outcome: with zero errors anywhere.

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