Replace audio

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

With no annotations provided, the description carries the burden of disclosing behavior. It reveals a non-obvious trait: 'The output ends when the shorter of the two ends, unless loop_audio is set.' This gives the agent important predictive insight into output duration. However, it does not mention other side effects like whether the input file is modified or whether there are format constraints.

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 two sentences, front-loaded with the primary function, and includes a specific behavioral detail. Every word earns its place; there is no redundant or vague phrasing.

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 simple 4-parameter tool with no output schema and no nested objects, the description covers the essential purpose, parameter interaction, and a key behavioral rule. It is adequate for an agent to invoke correctly, though it could potentially mention output behavior or compatibility but this is not critical.

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 adds value by explaining the interaction between video length, audio length, and loop_audio: 'output ends when the shorter of the two ends, unless loop_audio is set.' This goes beyond the individual parameter descriptions and helps the agent understand how parameters combine.

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 action: 'Replace a video's audio track with a different audio file' followed by concrete examples ('background music or a voiceover'). This distinguishes it from sibling tools like extract_audio, remove_audio, and adjust_volume, which serve different purposes.

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 context for when to use the tool ('e.g. background music or a voiceover') and explains the default behavior with loop_audio, implying when that parameter should be set. It does not explicitly name alternative tools for different audio operations, but the purpose is clear enough for an agent to infer appropriate usage.

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