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

Annotations already declare readOnlyHint=false, idempotentHint=true, destructiveHint=false, openWorldHint=false, so the safety and repeatability profile is covered. The description adds real context beyond that: a hard cardinality constraint of two-to-four panels, the optional label/expansion behavior, and the fact that it returns rectangles rather than rendering. It does not mention whether it replaces an existing stack or how start/end interact with placement.

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?

Two tight sentences, front-loaded with the core action and ending with the return value. Nothing is redundant, though the second sentence could be folded in without loss.

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 9-parameter, low-coverage mutation tool with no output schema, the description is thin: it covers panel count, labels, and expansion but not timing (start/end), direction behavior, or what id does. An agent could call it but would be guessing on most parameters and on how it differs from compose_panels.

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 only 11% (just project_id), so the description must compensate and largely does not. It maps loosely to panels (two-to-four), labels, and grow/grow_at ('panel expansion'), but leaves start, end, direction, and id entirely unexplained — including the enum values auto/vertical/horizontal and what start/end mean for the composed stack.

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?

The description gives a specific verb and resource: 'Composes two to four independent footage panels' and states the output ('panel rectangles'). It is clear what the tool does, but it never distinguishes itself from the close sibling compose_panels (or add_collage), so an agent cannot tell which to pick from the description alone.

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 when-to-use or when-not-to-use guidance. The only implied usage is via 'for subsequent layout operations', which hints at ordering but names no alternative tool or precondition for choosing this over compose_panels.

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