Play from YouTube

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

Beyond annotations (openWorldHint, non-read-only), the description reveals the tool streams media, implying side effects and external dependencies. This contextualizes the annotation values.

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 with no superfluous words. Front-loaded with the core action, then clarifying input types. Efficiently scoped.

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 3-param tool with full schema and annotations, the description adequately covers core behavior. Missing a note on how multiple results are handled (queuing) is covered by schema, so acceptable.

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 already explains each parameter thoroughly. The description echoes the query parameter's dual role (URL vs search term) but adds no new semantic value.

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 clearly states the tool searches YouTube and streams via mpv, distinguishing it from siblings like mpv_add or mpv_download. The verb-resource pair (search+stream YouTube) is specific and unambiguous.

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?

No explicit guidance on when to use this versus alternative tools (e.g., mpv_add for local files). The purpose is clear, but an agent might benefit from hints about prerequisites (network) or fallback tools.

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