Set file ACL

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

Goes well beyond the annotations (which already cover destructive/read-only/idempotent/open-world) by disclosing the auth requirement ('assets:write' permission), the subtle dropping of rules referencing nonexistent users, and the need to verify the returned ACL. These are genuinely useful mutation behaviors not derivable from the hints.

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?

Reasonably sized and front-loaded with the core action; each sentence carries substantive information. Slightly verbose with the formatting/bold auth line, but nothing is filler.

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?

For a destructive, open-world mutation tool with no output schema, the description covers auth requirements, ACL semantics, edge-case behavior (dropped rules), and response verification. It leaves the `account`/`confirm`/`payload` body-variant parameters to the schema, which is acceptable given full schema coverage.

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 coverage is 100%, so baseline is 3; the description rises above it by explaining the semantic consequence of the `default` enum values ('allow' with no rules makes the file public; 'forbid'/'hide' restricts) and the dropped-rule behavior for user rules. It adds meaning beyond the raw schema text.

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?

States a specific verb and resource ('Replaces the Access Control List of a fal CDN file'), which cleanly distinguishes it from the read-only sibling get_storage_file_acl. An agent knows exactly what this tool mutates without opening the 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?

The description establishes the tool's purpose and effects ('makes the file public', 'restricts it to the rules you provide'), which implies when to use it, but it never explicitly states when to choose this over get_storage_file_acl or other storage tools. Usage is left to inference.

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