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.

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

Annotations already declare readOnlyHint=true, so the safety profile is covered. The description adds genuinely useful context beyond that: the concrete storage location and the 'newest first' ordering, which an agent cannot derive from the empty schema. It omits pagination/result-size behavior, keeping it from a 5.

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?

A single sentence with the action, target, location, and ordering front-loaded. Every clause earns its place and nothing is padded.

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-parameter, read-only listing tool with no output schema, the description covers what is listed, where, and in what order. It could note the shape of the returned entries (filenames vs. metadata) since no output schema exists, but the gap is minor.

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?

The tool takes zero parameters, so the baseline is 4 and there is nothing for the description to clarify or compensate for. It adds no misleading parameter language either.

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 ('List MP3 files already downloaded'), plus the exact directory and sort order, which cleanly separates it from the write-oriented download_mp3 and search_youtube siblings. It stops just short of 5 because it never names the alternatives it is contrasted 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?

There is no explicit when-to-use statement, but the scope ('already downloaded to /root/Music/yt-audio-mcp') strongly implies this is a post-download inventory check rather than a discovery tool. No alternatives or exclusions are mentioned, so the guidance is only implied.

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

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds value beyond that by disclosing the shape of the result (video IDs/URLs) in the absence of an output schema. It omits result ordering, pagination, and any rate-limit behavior.

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?

A single front-loaded sentence with zero filler; the action, the return type, and the downstream consumer all appear immediately.

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 correctly shoulders the return-value explanation (video IDs/URLs). Combined with the annotations and a mostly simple two-parameter schema, this is nearly complete; only limit semantics and empty-result behavior are 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 coverage is only 50%: query is documented with an example format, but limit has no description anywhere. The tool description adds no parameter-level meaning at all, so the agent gets no guidance on what limit controls or what the default of 5 implies.

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 ("Search YouTube") plus the concrete return payload ("video IDs/URLs"). It also names the downstream sibling download_mp3, so an agent can place it in the pipeline without opening any other tool.

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 establishes clear context by saying results "can be passed to download_mp3," which tells the agent this is the search step that precedes downloading. It stops short of explicit when-not guidance or naming list_downloads as an alternative for retrieval of already-downloaded items.

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