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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world), and the description adds real behavioral context: the response is a browsable menu with a real example, includes per-shape photo capacities, and notes that photos fill shapes 'without repeats'. It stops short of describing response structure or error behavior, but the added value over annotations is substantial.

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 sentences, no filler, and the purpose is front-loaded before the invocation guidance. The long parenthetical shape enumeration is dense but carries genuine information about output scope.

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?

With no input parameters and no output schema, the description carries the return-value burden itself and does so: it says what the menu contains, that examples are included, and what the photo capacities mean. An agent has everything needed to decide to call it and to interpret what comes back.

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?

The tool takes zero parameters and the schema is an empty closed object, so there is nothing for the description to disambiguate. Baseline for a no-parameter tool is 4; the description correctly implies a parameterless, call-and-read operation.

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 (shows/lists) and resource (the menu of Collager.ai collage shapes), then enumerates the concrete shape families (hearts, numbers, words, circle, star, flower, grid, custom mask) and their photo-count ranges. It explicitly links the list to the sibling make_shape_collage, so an agent can tell the two apart without opening either 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?

Gives explicit trigger conditions: 'Call it first when the user only mentions Collager.ai, says hello to it, or asks what it can make.' This is a concrete routing rule rather than an implied one, and it positions the tool ahead of the sibling collage tools in the flow.

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