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

Annotations already declare readOnlyHint, idempotentHint and openWorldHint, so the safety profile is covered. The description adds genuinely useful context beyond them: the output is a 16-bit PCM WAV returned as base64, fades are linear and optional, and only WAV input is handled. It does not discuss failure modes (e.g., range exceeding clip length) or output size limits, keeping it at a 4.

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, front-loaded with the core purpose and output format, followed by the input-format restriction. Nothing is redundant and every clause carries 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?

For a straightforward audio transform with an output schema and rich annotations, the description covers format support, output encoding and fade behavior. It omits edge-case behavior such as ranges beyond the clip length or error signaling, which for a tool with a nested file object and five parameters would be a useful addition.

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 80%, so the schema already documents file, startSec, endSec, fadeInSec and fadeOutSec with types, defaults and bounds. The description only restates that fades are optional and that output is 16-bit PCM; it adds no meaning to startSec/endSec semantics beyond the schema. 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?

Specific verb (trim) + resource (WAV audio file) + scope (time range, optional fades, 16-bit PCM WAV base64 return). The constraint 'Only WAV is accepted; the web UI handles MP3/OGG/M4A' makes the boundary of the tool unambiguous, so an agent can tell immediately whether this tool applies to a given file.

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 clear selection condition: use this for WAV, use the web UI for MP3/OGG/M4A. That is a real when-not rule. It stops short of stating prerequisites (e.g., that startSec must precede endSec within the clip length) or what happens on out-of-range input, so it is clear context rather than full routing guidance.

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