list_image_models

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

Annotations already establish readOnlyHint=true, destructiveHint=false, so the safety profile is covered. The description adds genuinely new behavioral context: pricing is live per row, missing prices never suppress a model from the listing, and default_model_type is the fallback selector. It does not discuss pagination or refresh behavior, keeping it just shy of a 5.

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 sentences, all load-bearing, with the core purpose front-loaded before the fallback and quoting caveats. The middle sentences are dense but each conveys a distinct rule, so nothing reads as 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?

With no output schema, the description carries the burden of describing the return and does so usefully: a model catalog, per-model capabilities, model.pricing rows, and an independent pricing_status, plus default_model_type. An agent knows enough to consume and act on the result, though the exact shape of the capabilities object remains unspecified.

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, so the baseline is 4; there is no parameter surface the description needs to disambiguate. The description correctly adds no invented parameter semantics.

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 names a specific verb and resource ('List the complete Web image model catalog and per-model capabilities') and enumerates what the listing contains, including price rows and pricing_status. This distinguishes it cleanly from the parallel list_video_models, list_music_models, and list_tts_models siblings without needing to name them.

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?

It gives conditional workflow guidance: when no model is specified, fall back to the returned default_model_type, and 'use an exact quote before generation' which implicitly routes the agent toward the cost-estimation step. It stops short of explicitly naming estimate_image_cost as the next call or stating when not to use this tool, so it is clear context rather than a full when/when-not/alternative matrix.

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