ffmpeg__mux_audio

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 original audio track is discarded, states that output is JSON in stdout, and notes default behaviors for audio_delay_ms and reencode_audio. This adds significant behavioral context beyond the schema.

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 well-structured with a clear opening sentence, @remarks, and @param lines. It is longer than minimal, but the length is justified by the complete parameter documentation needed due to zero schema coverage. Every sentence contributes value.

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 states the return format (JSON with output_path and applied parameters) and key side effects (original audio discarded, stream copy default). It also covers all six parameters with defaults and behavior, making the tool fully understandable for an agent.

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 0%, so the description's @param annotations are essential and fully compensate. Each parameter gets meaningful explanation: video_path discards original audio, audio_delay_ms positive means delay, reencode_audio default false means stream copy, and __mcp_response_mode has an enum. This is comprehensive parameter semantics.

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 opening sentence clearly states the tool's function: 'Replace or attach an audio track to a video by muxing a separate audio file.' This is specific and distinguishes it from sibling tools like mix_audio_tracks by explicitly noting that the original video audio is discarded.

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 clear usage context with 'Typical use: attach a mixed or dubbed audio track to a graded video.' However, it does not explicitly mention alternatives or when not to use this tool, 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.