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

Annotations already declare readOnlyHint=false and destructiveHint=false, but the description adds two facts the annotations cannot: the call spends credits, and existing user-owned pieces are preserved while director pieces are regenerated. That preservation/cost context is exactly the kind of behavioral detail that matters for a mutating, open-world tool; missing only permission or failure modes.

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?

The core statement is front-loaded and short, which is good, but the trailing fragment 'credits: price.redesign.credits.' duplicates the schema's credits description and reads as a leftover snippet rather than an earned sentence.

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 three-parameter mutation that costs credits, the description covers cost and what is preserved versus regenerated, and no output schema exists so return values needn't be explained. It stops short of saying whether the redraw is asynchronous or whether the returned lookbook reflects the new pieces, but overall it is sufficient to call correctly.

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 all three parameters (note, credits, lookbook_id) are already documented in the schema. The description echoes 'with a note' and 'spends credits' but adds no format, bounds, or example beyond that, so baseline 3 is appropriate.

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 ('Redesigns') and a specific scope (the director's pieces in a lookbook) with the note-based behavior made explicit. It implicitly distinguishes itself from redraw_music_video_lookbook_piece (one piece) by operating on 'pieces' plural, though the term 'director's pieces' is jargon that isn't defined.

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?

There is no explicit guidance on when to choose this over redraw_music_video_lookbook_piece, update_music_video_lookbook, or keep_music_video_lookbook_piece, all of which sit adjacent in the sibling list. The line 'The user's own pieces stay' implies a scope distinction but never converts it into a use-when/use-instead rule.

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