Update asset character

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

Annotations already declare destructiveHint=true, idempotentHint=false and openWorldHint=true, so the safety profile is covered. The description adds one non-obvious behavior — unresolved ID references are materialized before character state is added — which hints at a side effect beyond annotations. It still does not disclose the confirm requirement, permission needs, or reversibility of the mutation.

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?

Three compact sentences with the resource and scope front-loaded, then the reference-image preference, then the materialization note. Every sentence is relevant, though the first sentence partly restates the title.

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 10-parameter mutation tool with a nested payload object, no output schema, and fully documented parameters, the description covers purpose, image-reference format, and one behavioral side effect. The remaining rules (mutually exclusive body forms, confirm flag) are fully specified in the schema, so nothing critical is missing.

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%, so the schema already documents all ten parameters thoroughly. The description's reference_images guidance duplicates the schema's own parameter text verbatim, adding no new meaning beyond it. Baseline 3 is appropriate when the schema carries the load.

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 ('Update an asset character') plus the scope ('authenticated user's fal Assets library'), which lets an agent distinguish it from create_asset_character and delete_asset_character. It is clear but never restates the required character_id target role or contrasts against those siblings explicitly.

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?

Offers real guidance for one field ('Prefer vector IDs or request IDs in reference_images... use fal-hosted image URLs only for standalone images'), which is genuine when-to-use advice. However, there is no guidance on when to update vs. create/delete a character, no mention of when the confirm flag is needed, and no exclusions for the alternative body forms (payload vs. flat flags).

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