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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered; the description adds real value by disclosing the two operating modes (catalog listing vs single-model detail) and that prices are quoted in USD. It stops short of noting rate limits or whether the catalog is static.

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, zero filler, with the primary listing behavior front-loaded and the follow-up workflow hint second. Every clause carries information an agent needs.

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 annotations covering safety, an output schema covering the return shape, and only one optional parameter, the description supplies everything an agent needs to call it correctly and to know why it would. Minor gap: it doesn't clarify how granular 'modes' are or whether the catalog is stable across calls.

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 100% and the single `model` parameter already carries a description in the schema. The description restates that passing it yields full parameter details; that meaning is already in the schema, so the added value is marginal beyond the baseline for high-coverage schemas.

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 ('List the available video and image models') and enumerates the returned fields (modes, resolutions, durations, unit prices in USD). This clearly separates it from siblings like estimate_cost and generate, which consume rather than describe model metadata.

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?

Explicitly sequences the workflow: pass `model` to get full parameter details for that model *before* calling estimate_cost or generate. It names the downstream tools and the condition that selects the detail mode, leaving nothing to inference.

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