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

With no annotations, the description carries the behavioral burden. It discloses that the tool downloads videos (including from local paths), skips near-duplicates, returns absolute file paths, and that those paths must be read as images to see the video. It does not mention potential network/auth requirements or failure modes, but the key behavior is clearly conveyed.

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?

Three sentences with no fluff: the first states the core action, the second explains the output and how to use it, and the third gives usage context. Purpose is front-loaded, and every sentence earns its place.

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 and 6 parameters, the description plus schema provide enough to call the tool correctly. It explains the manifest return value and that frames are returned as paths to read. It could mention the contact-sheet output, but that is captured in the schema, so 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?

Schema description coverage is 100%, so the baseline is 3. The description does not add parameter-specific meaning; it simply gives overarching context about frame extraction, which is already supported by the schema's field-level descriptions.

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 a specific action ('extract') and resource ('visually distinct frames from a video'), and names supported sources. It also tells the agent when to use it ('whenever you are asked about the contents, design, or UI of a video'), which distinguishes it from the sibling framedeck_info by use case.

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?

It gives an explicit when-to-use condition: 'Use this whenever you are asked about the contents, design, or UI of a video.' It does not explicitly say when not to use it or compare with the sibling framedeck_info, so it stops short of a full 5.

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 present, the description carries the behavioral burden and does so well by disclosing that it does not download the video and is inexpensive. It could add more about response format or error behavior, but the non-destructive nature is clearly conveyed.

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, each earning its place: the first states the operation and scope, the second gives the cost and routing rationale. No filler or redundant restatement.

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 single-parameter info tool with no output schema, the description supplies the return fields and a clear use case, which is largely complete. It leaves minor gaps such as exact URL format and explicit alternative mention, but nothing blocks correct invocation.

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 schema has zero description coverage and only a string 'url'. The description gives the URL its semantic role — identifying a video whose metadata will be fetched — and previews the returned fields, adding meaning beyond the bare schema.

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?

Starts with a specific verb and object ('Fetch a video's metadata') and lists concrete fields (caption, author, duration). The 'without downloading it' phrasing distinguishes it from a potential extract/download sibling, so an agent can tell it apart from framedeck_extract.

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?

It gives a clear selection rule: use this as a cheap first call when the caption alone may answer the question. It does not explicitly name the alternative or state when not to use it, but the intended routing is strongly implied.

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