Is this export in the npm package's published type declarations

$0.005 USDC per call · Developer and security · POST /api/v1/symbol-exists · Id symbol-exists

Checks that up to 20 named exports (functions, classes, constants, types, default) exist in the .d.ts files published for an exact npm package version, read from jsDelivr, for coding agents that may be calling an API that does not exist. Follows export lists and relative export-star re-exports within the package (at most 7 files) and reports when the export surface cannot be fully enumerated. Never downloads or runs the package code; packages typed only through @types or without declarations return unsupported; does not check signatures or arguments.

What you get

Catches hallucinated API names before the build or the reviewer does.

Call it

Send the JSON body below to https://agents.writerslogic.com/api/v1/symbol-exists. An unpaid request answers 402 with the price and how to pay; a request that fails with a 5xx status is not charged.

curl -i -X POST https://agents.writerslogic.com/api/v1/symbol-exists \
  -H 'content-type: application/json' \
  -d '{"package":"nanoid","version":"5.0.7","symbols":["nanoid","customAlphabet","nonexistentFn"]}'

Input

Field	Type	Required	Description
`package`	string; length 0..214	yes	npm package name.
`version`	string; length 0..64	yes	Exact version or dist-tag (jsDelivr resolves it).
`symbols`	array<string; length 0..100>; max 20 items	yes
`entry`	string; length 0..100	no	package.json exports key, default '.'.
`typesPath`	string; length 0..200	no	Declaration file path inside the package, overriding package.json resolution.

Example request body

{
  "package": "nanoid",
  "version": "5.0.7",
  "symbols": [
    "nanoid",
    "customAlphabet",
    "nonexistentFn"
  ]
}

Result

The response is { "data": ..., "_provenance": ... }. data carries these fields; _provenance is a signed W3C Verifiable Credential with a C2PA-style manifest, checked free at POST /api/v1/verify-provenance.

Field	Type	Required	Description
`status`	string; one of "pass", "fail", "unknown", "unsupported"	no	pass: every rule held. fail: a rule was violated (see witnesses). unknown: the input lacks the evidence to decide. unsupported: outside what this engine covers. Missing evidence is never a pass.
`package`	string	no
`version`	string	no
`complete`	boolean	no	True when the whole export surface was enumerated, so a missing symbol is a real absence.
`filesRead`	array<string>	no
`incomplete`	array<string>	no
`symbols`	array<object>	no
`witnesses`	array<object>	no
`versions`	object	no	Every semantic dependency of this answer (engine, tables and their as-of dates, tokenizer, calendar, rounding profile).
`limits`	array<string>	no
`deterministic`	boolean	no	Always true: pure code, no model.

Pay and connect

Available through: x402 (USDC on Base), MCP. MCP clients reach it through the code-preflight-kit package.

Machine-readable

This agent as JSON (schemas, example, OpenAPI operation)
Free signed sample response
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