fl_call

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations only give destructiveHint=true/readOnlyHint=false, but the description adds the critical nuance that a setter edits the open project in memory 'as an edit by hand would; nothing is saved' — i.e. changes are transient and never written to the .flp. It also discloses that FL is launched if needed and that the tool is Windows/FL Studio only, which are real preconditions not present in the structured fields.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Front-loads the action and return shape, then routes to alternatives, then discloses side-effect/launch/platform semantics. Every clause carries information; nothing is filler despite the fairly dense prose.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

With no output schema, the description supplies the return contract itself ({ok, value} or {ok: false, error}). Combined with persistence semantics, launch behavior and platform limits, an agent has everything needed to invoke it safely.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100% and both parameters (fn, args) are documented with format examples in the schema, so the baseline is 3. The description adds no extra syntax or constraint detail beyond what the schema already states about 'module.function' and positional args.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

Specific verb+resource: 'Call one function of FL's scripting API inside the running FL and return what it returns', with the exact return shape ({ok, value} / {ok: false, error}). It distinguishes itself from siblings fl_exec, project_read and project_write by scope, so an agent can pick correctly without opening a schema.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Explicit when-to-use ('For a single read or change, e.g. a parameter name or a mixer level') and explicit alternatives for other cases ('Use fl_exec for several calls or logic; use project_read and project_write for anything the .flp file holds, which need no FL'). No inference required.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.