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

Annotations already indicate the tool is non-read-only and non-destructive, and the description adds that it uses FFmpeg and produces an MP3. However, it does not state what the tool returns or where the merged file is placed, which is a notable gap given the absence of an output 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 core statement is one efficient sentence with the action and key constraint front-loaded. The leading 'Merge Audio' is somewhat redundant with the title, and the '[category: media]' tag adds little, but overall it is concise and scannable.

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 one-parameter tool with full schema documentation and annotations, the description covers purpose, input requirements, and output format. The main gap is output handling, but this is minor for such a focused merge operation.

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 only parameter, 'files', is fully documented in the schema with supported formats and a minItems constraint. The description repeats 'at least 2' but adds no new parameter meaning, so schema coverage carries the weight; baseline 3 applies.

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?

Description uses a specific verb and resource: 'Concatenate multiple audio files (at least 2) into one MP3.' It clearly distinguishes from siblings like media_extract_audio and media_trim_audio by focusing on merging multiple inputs into a single output.

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 intended use is clear: use this tool when concatenating two or more audio files into one MP3. It does not explicitly name alternative tools or exclusion conditions, but the phrase 'Concatenate multiple audio files' provides enough context to avoid confusion with sibling media tools.

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