Download MP3 from YouTube

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

Annotations only declare readOnlyHint=false and openWorldHint=true; the description adds real behavioral context beyond that: the exact on-disk destination (/root/Music/yt-audio-mcp) and the cache-then-refetch semantics tied to force. It still omits failure modes (invalid URL, geo-blocked or age-restricted video, network errors) and whether partial downloads are cleaned up.

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 zero filler; the primary action and the artifact come first, and the caching caveat follows. Nothing is redundant with the title.

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 state the destination path and the disk-cache return behavior, which is the key information. It stops short of saying what handle or metadata is actually returned to the caller (e.g. file path vs. confirmation), which would fully close the gap.

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 each parameter is already documented in the schema, including the force default and the bitrate enum. The description's only parameter-relevant addition is the force behavior, which largely restates the schema's 'Re-download even if the file already exists'. Baseline 3 is appropriate.

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 (Download) plus resource (audio of a YouTube/YouTube Music video) and the output artifact (MP3 file). An agent can immediately tell this apart from search_youtube and list_downloads, which discover content and enumerate files rather than producing one.

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?

The description gives one concrete conditional rule ('Already-downloaded videos are returned from disk unless force=true'), which is useful. It never mentions the sibling tools, so it does not tell the agent to search first to obtain a URL or to use list_downloads to verify an existing file, leaving selection between tools to inference.

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