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

readOnlyHint=true already declares the safe read profile, and 'Free' adds a useful cost attribute. The exclusion note ('Video models that cannot be bought here are left out') is genuinely behavioral context, but there is no statement about pagination, caching, or auth since none is needed. Credit-worthy but modest beyond the annotation.

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?

Front-loads the key facts ('Free', what it returns) and uses clear Args/Returns structure. The return-field enumeration is long but earns its place because no output schema exists.

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 return-value burden and does so with a concrete shape including price and duration fields. For a one-enum-param read tool with readOnlyHint coverage, this is close to complete.

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 0%, but the single parameter is an enum whose five values the description repeats verbatim, so it adds little on that axis. It does add meaning by framing kind as selecting an output category and by noting the video case has an availability filter. Adequate, not compensating richly.

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+resource: lists the models ViralMint offers for one kind of output, along with their prices. The scope ('one kind of output', via the kind arg) is clear and distinguishes it from sibling generation tools, though it doesn't name a sibling it competes 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 implied rather than stated: 'Use the ids in generation tools' tells the agent this is a lookup step before generate_image/generate_video_clip/etc. There is no explicit when-not guidance beyond the note that unbuyable video models are omitted.

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