Frame At

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

With no annotations provided, the description bears full responsibility for behavioral disclosure. It states that it extracts a single frame from a specific timestamp, but does not mention side effects (e.g., it is read-only), how invalid timestamps are handled, what the output is (file path, binary?), or any performance considerations. The behavioral transparency is minimal.

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 extremely concise with just two sentences. The first sentence states the core action, and the second provides a practical usage example. Every word is essential, and there is no redundant information.

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 being a simple tool, the description lacks important context: there is no output schema, so the return value is unclear; error handling or constraints (e.g., video format support) are not mentioned; and the parameter 'resolution' default value (1456) is unexplained. Given the low parameter coverage and no behavioral details, completeness is insufficient.

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 4 parameters with only 25% description coverage (only 'timestamp' has a description 'HH:MM:SS'). The description itself adds no parameter meaning beyond what the schema provides. For example, 'video_path' lacks any description, and 'resolution' and 'format' are not elaborated. The description does not compensate for the low schema coverage.

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 'Extrai um único frame de um timestamp exato' (extracts a single frame from an exact timestamp), distinguishing it from sibling tools like 'extract_frames' (plural) which likely extracts multiple frames. The example 'útil para o que tem em 1:30?' provides a concrete use case, making the purpose precise and actionable.

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 a usage example ('útil para o que tem em 1:30?'), which implies when to use it (inspecting a specific timestamp), but it does not explicitly state when not to use it or mention alternatives like 'extract_frames' for batch extraction. The guidance is implicit and lacks exclusion criteria.

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