Module args 

Typed extraction of tools/call arguments.

Every tool used to read its optional arguments with a bare args.get("max_tokens").and_then(Value::as_u64), so the None branch — “the caller sent something, but not of the declared type” — was indistinguishable from “the caller sent nothing” and the flag was simply omitted from the spawned argv. That is a wrong-answer channel: the client believes it asserted something the server never applied, and the result JSON echoes the CLI’s default so the drop is undetectable downstream. apr.qa’s assert_tps is the sharpest case — passed as a JSON string it disarmed the throughput gate entirely (#2403).

The rules here are deliberately narrow:

• absent or JSON null → Ok(None) (the argument is optional)
• the declared JSON type → Ok(Some(v))
• a string that parses exactly into the declared type → Ok(Some(v)). LLM clients routinely emit numbers as JSON strings, so "8" for an integer is the common path, not an exotic one — coercing it is what the caller meant and it is lossless.
• anything else → Err(message), which the tool turns into an isError: true result. This matches the one field that already validated before this module existed, apr.serve’s port.

Nothing is ever silently dropped.

Functions

json_type_name

JSON type name as it appears in a JSON Schema type keyword.

opt_bool

Extract a boolean argument ("type": "boolean").

opt_f64

Extract a floating-point argument ("type": "number").

opt_str

Extract a string argument ("type": "string").

opt_u64

Extract a non-negative integer argument ("type": "integer").

require_str

Extract a required string argument from a tools/call arguments object.

required_str

Extract a required string argument, reporting absence and wrong type distinctly.

Type Aliases

ArgResult

Ok(None) = absent, Ok(Some(v)) = present and usable, Err = present but not convertible to the declared type.