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

With no annotations, the description carries the full burden and delivers real behavioral context: a 6-hour link validity window, deciphered (ready-to-download) URLs, the muted-high-quality caveat, and a per-call cost of 2 credits. It omits auth requirements and the exact return shape, but the disclosed traits are the important ones.

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 what the tool returns and packs several important facts (expiry, caveat, muxer, billing) into a few sentences. The leading '**object**' token is wasted noise, keeping it just short of ideal.

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 no-annotation, no-output-schema tool, the description covers the duration of validity, what the result contains, the muting caveat, and cost. Only parameter-level meaning and any auth/prerequisite detail are left unaddressed.

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 description coverage is 67%, with filter and quality well documented in the schema while id is only exampled. The description adds nothing about id, filter, or quality semantics, so it neither compensates for the gap nor improves on what the schema already provides.

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: grabbing YouTube download links from the Google Video server. It clearly distinguishes itself from the get_info* metadata siblings and points at the muxer resource, so an agent can identify it without opening the 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 a concrete condition for using the related /mux endpoint to merge audio and video, which implicitly frames when this tool alone is insufficient. It does not, however, contrast itself against the get_info family or state prerequisites for calling it.

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