audio_info

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

Goes well beyond the annotations (readOnlyHint/openWorldHint), which only cover the safety profile. It discloses the FFmpeg dependency, the concrete failure mode and message when FFmpeg is absent, how formats map to format/subtype/decoded_via, and that a directory path triggers recursive listing.

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?

Front-loaded with the core value ('Fast metadata without decoding'), followed by concrete detail. Slightly dense in the FFmpeg/container/codec sentence, but every clause carries information an agent needs; nothing is 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?

With no output schema, the description carries the return-value burden and does a fair job by naming the reported fields and the decoded_via/format/subtype semantics, plus the directory-listing variant. It stops short of specifying ordering or how many files a directory listing returns.

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% for the single `path` parameter, so the description must compensate. It does: `path` is documented as accepting either a file or a directory, with recursive enumeration behavior on directories, which is meaningfully more than the bare string schema.

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 (read/report metadata) and an explicit scope: 'Fast metadata without decoding: format, sample rate, channels, duration.' The 'without decoding' qualifier and the enumerated fields clearly distinguish it from heavier siblings like audio_analyze or audio_transcribe.

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?

Usage is implied rather than stated: the 'without decoding' framing and the directory behavior hint at when this cheap metadata call is the right choice, but no sibling is named and there is no explicit when-not guidance (e.g. 'use audio_analyze if you need spectral content').

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