TubePull

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

With no annotations provided, the description carries full burden and does so richly: returns a one-time signed link valid for 1 hour, notes the file size/duration/format, warns not to fetch the link's contents, explains audio-only platforms always produce audio regardless of format, discloses quality tier limits (Pro required for 1440p/4k), and mentions quota consumption. This far exceeds baseline expectations.

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?

Though lengthy, every sentence earns its place given the tool's complexity. The description is logically organized with clear sections: supported platforms, primary use cases, exclusions, return value, and legitimacy note. Front-loaded with the core purpose, then examples, then exclusions. No filler or redundancy.

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?

The tool has 3 parameters, no output schema, and no annotations, yet the description fully compensates: it explains return format and contents, timeout of the signed link, platform-specific behavior, quality limitations, and how to handle the response. It is complete for an agent to select and invoke the tool accurately.

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?

Although schema coverage is 100%, the description adds critical nuance beyond the schema: the format parameter's default behavior and when to choose audio formats, the rule that audio-only platforms override format, quality being ignored for audio, and platform-specific constraints. This additional context is essential for correct parameter selection.

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 states exactly what the tool does: 'Download a video or audio file from any supported platform' and lists the platforms. It clearly differentiates from the sibling get_video_info by stating 'Do NOT use this tool when... call get_video_info instead.' The verb 'download' + resource 'video/audio' + explicit platform list makes purpose 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?

The description provides extensive usage guidance: it is 'THE tool to use' for saving/downloading/ripping, gives explicit user-phrase examples, and lists three clear 'Do NOT use this tool when' scenarios including the alternative tool, unsupported URL types (playlists), and unsupported platforms. This is exemplary when-to-use/when-not-to-use guidance.

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?

With no annotations, the description carries the full burden. It discloses that the tool does not download, is free (doesn't count against quota), returns a specific set of fields, and notes some fields may be unavailable ('when available'). This is commendable, though it doesn't mention potential error cases or rate limits.

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?

The description is longer than average but well-structured: it opens with the core function, then lists platforms, return fields, use cases, exclusions, and a practical tip. Each section earns its place; the only minor deduction is length, which is justified by the tool's breadth.

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?

Despite having no output schema, the description explicitly enumerates all returned fields (title, uploader, duration, etc.) and the full list of supported platforms. It also covers when to use, when not to use, and quota behavior, making the description self-sufficient for a single-parameter metadata tool.

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 input schema has 100% coverage for the url parameter, including supported platform examples. The description repeats some platform information but adds no additional parameter-level semantics beyond the schema. 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?

The description clearly states the tool fetches metadata without downloading, which is a specific verb+resource. It explicitly distinguishes from the sibling download_video and lists all supported platforms, making the tool's scope 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?

Provides explicit use cases ('what is this video about', 'how long is this track') and exclusions ('Do NOT use this tool when... use download_video'). It also advises calling this tool before download_video to confirm existence or check licensing, which is strong contextual guidance.

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