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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. Beyond that, the description adds real context an agent could not infer: lifecycle states (active, deprecated with retires_at and successor, paused) and that price_from reflects credits at default settings — useful qualifiers that prevent misreading the numbers. It omits whether deprecated or paused models appear in the default unfiltered listing, which would have mattered for a lifecycle-aware tool.

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?

One front-loaded sentence with the resource first, then the returned fields in reading order. Dense but every clause carries information; the parenthetical about params.prompt and character limit is a bit crammed but still purposeful.

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 zero-required-parameter listing tool with no output schema, the description carries the return-shape burden well by naming each returned field, including pricing and lifecycle. What it leaves out is whether paused/deprecated entries are included by default and how to page or filter — minor for a small catalog but not nothing.

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 kind parameter is fully documented in the schema with its enum values, so the baseline is 3. The description adds nothing about the filter and in fact mentions only image and video models while the schema also accepts "3d", leaving a small gap between prose and contract.

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?

Opens with a specific verb and resource ("Lists Tevyon's image and video models") and enumerates the fields returned, so the agent knows exactly what it gets. It does not distinguish itself from the sibling list_director_models, which is the one nearby tool an agent could confuse it with.

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 only implied by the verb: an agent can infer this is the discovery tool to call before picking a model. There is no explicit when-to-use, no guidance on choosing it over list_director_models or list_presets, and no mention of whether the optional kind filter should be used to narrow results.

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