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

Annotations only declare readOnlyHint and openWorldHint; the description adds genuinely useful behavior beyond them: the x402 payment model, the $0.004 USDC per-call cost, and the 20 MB input ceiling. It does not cover failure modes (e.g., unsupported containers, URL fetch errors), which keeps it short of a 5.

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 dense sentences: the inspect scope is front-loaded, then inputs, limits, and cost. Every clause carries information and none is redundant padding.

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 no-output-schema read tool, the description enumerates the returned metadata fields, the accepted input methods, the size limit, and the payment cost, which is everything an agent needs to invoke it correctly.

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 schema already documents url, filename, and file_base64, including the 20 MB limit. The description restates the same input modes and size bound without adding syntax, precedence rules, or format details beyond the schema, matching the baseline for full 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?

States a specific verb (inspect) and resource (audio/video file via ffprobe) and enumerates the exact fields returned (container, duration, bit rate, per-stream codec/resolution/frame rate/sample rate/channels/language). This clearly separates it from media_convert, media_trim, media_thumbnail and image_exif among siblings.

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 makes the intended use obvious (read metadata from an audio/video asset) and states accepted input modes and the 20 MB ceiling, but gives no explicit when-to-use vs when-not guidance and names no alternative sibling for related tasks. Usage is implied rather than directed.

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