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 cyanheads/clinicaltrialsgov-mcp-server --skill api-utilsgit clone --depth 1 https://github.com/cyanheads/clinicaltrialsgov-mcp-serverWrote 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/cyanheads/clinicaltrialsgov-mcp-server/api-utils)<a href="https://agentmods.dev/skills/cyanheads/clinicaltrialsgov-mcp-server/api-utils"><img src="https://agentmods.dev/badge/skills/cyanheads/clinicaltrialsgov-mcp-server/api-utils/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/cyanheads/clinicaltrialsgov-mcp-server/api-utils"><img src="https://agentmods.dev/badge/skills/cyanheads/clinicaltrialsgov-mcp-server/api-utils.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 | $0.00037 | $0.04999 |
| Opus 5 | $0.00018 | $0.02499 |
| Sonnet 5 | $0.00007 | $0.01000 |
| Haiku 4.5 | $0.00004 | $0.00500 |
Grade A, and why
api-utils scanned grade A with 0 findings 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 5d 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.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
This is a copy
100% identical to api-utils — 0 lines differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.
How it starts
The opening of the file, as written. The whole thing — 179 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Overview
Utility exports from @cyanheads/mcp-ts-core/utils. Utilities with complex APIs have dedicated reference files; simpler utilities are documented inline below.
Tier 3 = optional peer dependency. Install as needed (e.g., bun add js-yaml). All Tier 3 methods are async (lazy-load deps on first call).
Context parameters. Every helper below that takes a context accepts the handler Context as well as a RequestContext bag — pass ctx straight through, no slicing.
References
| Reference | Path | Covers |
|---|---|---|
| Formatting | references/formatting.md |
markdown(), MarkdownBuilder, diffFormatter, tableFormatter, treeFormatter — builder patterns, option types, style variants, usage examples |
| Parsing | references/parsing.md |
yamlParser, xmlParser, csvParser, jsonParser, pdfParser, dateParser, frontmatterParser — method signatures, option types, peer deps, Allow flags, PDF workflows |
| Security | references/security.md |
sanitization, RateLimiter, IdGenerator — config types, method details, sensitive fields, usage examples |
@cyanheads/mcp-ts-core/utils — network
| Export | API | Notes |
|---|---|---|
fetchWithTimeout |
(url, timeoutMs, context, options?: FetchWithTimeoutOptions) -> Promise<Response> |
Wraps fetch with AbortController timeout. timeoutMs bounds the whole exchange: on a 2xx carrying a body the returned Response is a passthrough wrapper that keeps the deadline armed until the body closes, errors, or is cancelled, so a stalled stream rejects the caller's .text()/.json() with the same Timeout error the header phase raises. status, statusText, headers, url, redirected, and type carry across the wrapper; the original body is locked by it, and bodyless/null-body responses (HEAD, 204/205/304) come back untouched. FetchWithTimeoutOptions extends RequestInit (minus signal) and adds rejectPrivateIPs?: boolean, expectedStatuses?: number[] (listed non-2xx statuses logged at debug not error, still thrown), errorBodyLimit?: number (bytes of a non-2xx body kept, default 500), and signal?: AbortSignal (external cancellation — an abort on it throws RequestCancelled (-32011), logged at info and outside withRetry's transient set, since the caller is gone and no retry can reach them). On a non-2xx, error.data carries status/body plus the legacy statusCode/responseBody aliases (identical values; consolidating in a future major); a body over errorBodyLimit is captured from both ends — 40% head, 60% tail, joined by …[N bytes elided]… — so a diagnostic behind a boilerplate preamble survives the cap, while a body still streaming at the 16 KiB scan ceiling stays head-only with a trailing …. SSRF guard (best-effort, not hard isolation): blocks RFC 1918, loopback, link-local, CGNAT, cloud metadata. DNS validation on Node, Bun, and Cloudflare Workers under nodejs_compat; hostname-only fallback otherwise. Both resolvers are queried — resolve4/resolve6 (c-ares) and lookup (the system resolver, which is what reads /etc/hosts, split DNS, and NSS modules) — and a non-global answer from either rejects. Runtimes differ in which resolver the connection uses (Bun 1.4 moved net.connect() on Linux to getaddrinfo while leaving dns.resolve*() on c-ares), so checking one alone leaves a name the other can see unguarded; each probe settles independently, so a resolver absent from the runtime is skipped rather than fatal. Manual redirect following (max 5) with per-hop SSRF check. DNS rebinding / TOCTOU gap — the validation lookup and fetch's own resolution are independent; pair with egress controls or a DNS-pinning fetch proxy for strong isolation. Error/log redaction: URLs written into thrown errors and log lines are reduced to origin + pathname — the query string (where API keys commonly ride: ?api-key=…, ?api_key=…) never reaches the client or the logs. The actual request still uses the full URL. |
withRetry |
<T>(fn: () => Promise<T>, options?: RetryOptions) -> Promise<T> |
Executes fn with exponential backoff. Retries on transient errors (ServiceUnavailable, Timeout, RateLimited); non-transient errors fail immediately. Honors an upstream Retry-After on data.retryAfter (delta-seconds or HTTP-date) over exponential backoff, capped at maxDelayMs; a requested wait beyond the cap fails fast rather than sleeping. On exhaustion, enriches the final error with attempt count in message and data.retryAttempts. Place the retry boundary around the full pipeline (fetch + parse), not just the network call. RetryOptions: maxRetries (default 3), baseDelayMs (default 1000), maxDelayMs (default 30000), jitter (default 0.25), operation (log label), context (RequestContext), signal (AbortSignal), isTransient (custom predicate). |
httpErrorFromResponse |
(response: Response, options?: HttpErrorFromResponseOptions) -> Promise<McpError> |
Maps an HTTP Response to a properly classified McpError — full status table including 401/403/408/422/429/5xx, body capture (truncated), retry-after header, optional cause. error.data carries status/body plus the legacy statusCode/responseBody aliases (identical values), so a consumer can classify either helper's error without knowing which raised it. Use this instead of hand-rolling if (status === 429) ... ladders. Reads the response body — clone() first if you need it elsewhere. HttpErrorFromResponseOptions: service? (logical name in message, e.g. 'NCBI'), captureBody? (default true), bodyLimit? (default 500), data? (extra fields merged into error.data), cause?, codeOverride? (per-status mapping override). Pairs naturally with withRetry — both classify codes the same way. A 501 also carries data.retryable: false, so retry fails it fast instead of re-asking for a method the upstream does not implement. |
httpStatusToErrorCode |
(status: number) -> JsonRpcErrorCode | undefined |
Sync status → code lookup. Returns undefined for 1xx/2xx/3xx. Use when you need just the code without a Response object handy. No status maps to InternalError — that code means this server failed, which a remote status cannot establish; every 5xx is ServiceUnavailable (or Timeout for 504) and so picks up withRetry's default transient policy. |
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
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.
- 5d ago Changed 593ea693c6ba
- 9d ago First seen · 179 lines · 37 tokens per session scan A f75eae5c2ac4
api-utils is a skill published in the GitHub repository cyanheads/clinicaltrialsgov-mcp-server (91 stars, last pushed 6d ago), licensed Apache-2.0. It adds 37 tokens to every session and 4,999 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 100% identical to api-utils, differing in 0 lines, and is treated as a copy.
Other skills, from other repositories
api-context
Canonical reference for the unified Context object passed to every tool and resource handler in @cyanheads/mcp-ts-core. Covers the full interface, its RequestContext base, all sub-APIs (ctx.log, ctx.state, ctx.requestInput, ctx.inputs, ctx.enrich, ctx.content), and when to use each.
field-test
Exercise tools, resources, and prompts against a live HTTP server via MCP JSON-RPC over curl. Starts the server, surfaces the catalog, runs real and adversarial inputs, and produces a tight report with concrete findings and numbered follow-up options. Use after adding or modifying definitions, or when the user asks to…
add-service
Scaffold a new service integration. Use when the user asks to add a service, integrate an external API, or create a reusable domain module with its own initialization and state.
api-auth
Authentication, authorization, and multi-tenancy patterns for @cyanheads/mcp-ts-core. Use when implementing auth scopes on tools/resources, configuring auth modes (none/jwt/oauth), working with JWT/OAuth env vars, or understanding how tenantId flows through ctx.state.
api-mirror
Stand up a persistent, self-refreshing local mirror of a bulk upstream dataset with the MirrorService (@cyanheads/mcp-ts-core/mirror). Use when a server wraps a large or slow API and should query a synced local index (embedded SQLite + FTS5) instead of paginating the live API per request.
api-utils
API reference for all utilities exported from @cyanheads/mcp-ts-core/utils. Use when looking up utility method signatures, options, peer dependencies, or usage patterns.