Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add magnusquest/startgg-mcp --skill api-errorsgit clone --depth 1 https://github.com/magnusquest/startgg-mcpWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/magnusquest/startgg-mcp/api-errors)<a href="https://agentmods.dev/skills/magnusquest/startgg-mcp/api-errors"><img src="https://agentmods.dev/badge/skills/magnusquest/startgg-mcp/api-errors/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/magnusquest/startgg-mcp/api-errors"><img src="https://agentmods.dev/badge/skills/magnusquest/startgg-mcp/api-errors.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00054 | $0.02747 |
| Opus 5.5 | $0.00022 | $0.01099 |
| Sonnet 5.5 | $0.00011 | $0.00549 |
| Haiku 4.5 | $0.00005 | $0.00275 |
Grade A, and why
api-errors scanned grade A with 1 finding against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Makes network callslowCapability
Not a fault in itself. Listed so you know the mod talks to something, and to what.
() => externalApi.fetch(url), How it starts
The opening of the file, as written. The whole thing — 257 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Overview
Error handling in @cyanheads/mcp-ts-core follows a strict layered pattern: tool and resource handlers throw McpError freely (no try/catch), the handler factory catches and normalizes all errors, and services use ErrorHandler.tryCatch for graceful recovery.
Imports:
import { notFound, validationError, McpError, JsonRpcErrorCode } from '@cyanheads/mcp-ts-core/errors';
import { ErrorHandler } from '@cyanheads/mcp-ts-core/utils';
Error Factories (Preferred)
Shorter than new McpError(...) and self-documenting. All return McpError instances. All accept an optional options parameter for error chaining via { cause }.
throw notFound('Item not found', { itemId: '123' });
throw validationError('Missing required field: name', { field: 'name' });
throw unauthorized('Token expired');
// With cause for error chaining
throw serviceUnavailable('API call failed', { url }, { cause: error });
Available factories:
| Factory | Code |
|---|---|
invalidParams(msg, data?, options?) |
InvalidParams (-32602) |
invalidRequest(msg, data?, options?) |
InvalidRequest (-32600) |
notFound(msg, data?, options?) |
NotFound (-32001) |
forbidden(msg, data?, options?) |
Forbidden (-32005) |
unauthorized(msg, data?, options?) |
Unauthorized (-32006) |
validationError(msg, data?, options?) |
ValidationError (-32007) |
conflict(msg, data?, options?) |
Conflict (-32002) |
rateLimited(msg, data?, options?) |
RateLimited (-32003) |
timeout(msg, data?, options?) |
Timeout (-32004) |
serviceUnavailable(msg, data?, options?) |
ServiceUnavailable (-32000) |
configurationError(msg, data?, options?) |
ConfigurationError (-32008) |
options is { cause?: unknown } — the standard ES2022 ErrorOptions type.
McpError Constructor
For codes not covered by factories (InternalError, DatabaseError, etc.):
throw new McpError(code, message?, data?, options?)
code— aJsonRpcErrorCodeenum valuemessage— optional human-readable description of the failuredata— optional structured context (plain object)options— optional{ cause?: unknown }for error chaining
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago First seen · 257 lines · 54 tokens per session scan A 0ccb95b3747a
api-errors is a skill published in the GitHub repository magnusquest/startgg-mcp (1 stars, last pushed 6mo ago), licensed Apache-2.0. It adds 54 tokens to every session and 2,747 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 1 finding (makes network calls). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.
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