@gnldev/tool-schema

Tool schemas that one provider accepts and another rejects, smoothed over.

The same JSON Schema does not travel cleanly between OpenAI, Gemini and Anthropic: one rejects format on strings, another dislikes certain nested constructs. This package rewrites a tool's schema for the model actually being called.

Install

Install: pnpm add @gnldev/tool-schema — or use it from a repo clone: pnpm install && pnpm -r build.

npm i @gnldev/tool-schema

Use

It is opt-in from @gnldev/durable:

import { defaultRules } from '@gnldev/tool-schema';

const gnl = createGnl({ ...config, schemaCompat: defaultRules });
// or per call: runDurable({ runId, journal, model, tools, schemaCompat: true, prompt })

Or directly:

import { applyToolCompat, detectModel, defaultRules } from '@gnldev/tool-schema';

const safe = applyToolCompat(tools, detectModel(modelId), defaultRules);

Exports

| Export | What it is | |---|---| | detectModel | Model id → which provider family it belongs to | | applyToolCompat | Applies the matching rules to a tool set | | defaultRules | The bundled rule set (OpenAI / Gemini / Anthropic) | | ToolSchemaRule | The rule interface — add your own for a provider not covered here |

Rules are ordinary objects, so a provider the default set does not know about is a rule you write rather than a fork you maintain.

One thing the OpenAI rule changes that you will see

OpenAI's strict mode has no notion of an optional property: every key of an object must be listed in required. So the rule lists them all — and widens the ones that were optional to also accept null, which is the only way strict mode can express "not supplied":

z.object({ to: z.string(), cc: z.string().optional() })
→  required: ["to", "cc"],  cc: { type: ["string", "null"] }

Without the second half the parameter is silently promoted to mandatory. Under strict: true the model then has no way to leave it out; without strict, required is still what it is told the tool wants. Keys that were genuinely required are left alone.

An enum gets null added to its values too, and a const is wrapped in anyOf rather than widened in place — in both cases changing only type would leave a node whose type admits null while its value constraint forbids it, which nothing can satisfy.

License

Apache-2.0 — see LICENSE.