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

Goes meaningfully beyond the annotations by disclosing that a new design is created and the original is kept (reinforcing destructiveHint=false with concrete consequence) and that a call takes about 45 seconds, which is real latency information the agent cannot get from structured fields. The 'only that change is made' scoping claim is also useful behavioral context. It does not state what permissions or credits are needed.

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 short sentences, front-loaded with the verb and the kinds of edits, followed by the two facts that matter for planning (new copy created, ~45s duration). No 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?

Covers the mutation semantics, non-destructiveness and latency well for a 3-parameter tool with full schema coverage. The notable gap is what comes back — presumably a new design id the agent would need for follow-up calls — which is unstated and there is no output schema to fall back on.

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 design id format, the instruction field and the product-shape behavior are already documented in the schema. The description reinforces that the instruction is plain words but adds nothing about the product parameter's effect on output shape.

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 ('Change a design or the user's own photo') and enumerates concrete edit types (text, name, date, frame, colours, removal) so the agent knows the input style is plain-language. It does not distinguish itself from the sibling restyle_design, which is the nearest alternative, leaving a small ambiguity.

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?

Usage is implied through the example edits and the note that 'only that change is made', which tells the agent this is for scoped, targeted edits rather than wholesale redesign. However there is no explicit when-not guidance and no mention of restyle_design or create_design as alternatives.

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