OpenCode Turns OpenAPI Into Agent Tool Contracts

anomalyco/opencode merged PR #35192 on July 4, adding OpenAPI.fromSpec to CodeMode with one generated tool per OpenAPI operation, host-side authentication resolution, skipped-operation reporting, response limits, and adapter tests.

For agent builders, the morning decision is to watch whether API integrations move from hand-wired prompts to inspectable contracts: the strongest public source keeps auth out of the model-visible schema and refuses API shapes the adapter cannot safely represent.

Facts

• The PR says fromSpec returns a tool subtree plus skipped entries instead of emitting broken tools for unsupported request or response shapes.
• The runtime resolves bearer, basic, header, and query credentials through a host auth.resolve callback, not through model-visible tool inputs.
• The merge adds roughly 490 lines across the OpenAPI adapter, runtime, README, export path, and package guidance.

Evidence

The public receipt is the merged OpenCode PR and commit, plus the README section that documents how generated tools are mounted under CodeMode and the runtime file that builds authenticated HTTP calls.

Context

This is page-one because it changes the tool surface. An agent no longer needs a bespoke wrapper for every API when a host can convert a public contract into tools, audit what was skipped, and keep secrets in the host boundary.

Limits

The adapter is a basic converter, not universal API automation. The PR explicitly leaves YAML parsing, some server overrides, cookie auth, multipart or binary bodies, streaming operations, and default-response schemas out of scope. What to watch: whether real API hosts adopt the adapter and whether skipped-operation reporting becomes part of agent integration review.