Index a signal (SignalLab)

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

With no annotations, the description carries the full burden. It does disclose the nature of the result (a non-destructive summary index) and lists the derived buckets, which is genuinely useful, but it says nothing about processing cost, latency, rate limits, or whether remote fetching has side effects. It adds context but leaves real operational traits unstated.

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?

Three tight sentences, front-loaded with what the tool produces before the usage note and input summary. Slight redundancy in re-listing the audio source, which the schema already covers, keeps it from a 5.

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?

There is no output schema, so the description must describe return values, and it does so thoroughly with the enumerated buckets and tag suggestions. What it omits — latency, remote-fetch behavior, failure modes — is minor for a local metadata-indexing tool with no annotations.

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 coverage is 100% and both parameters are fully documented in the schema, including the 'exactly one of url or path' constraint and inline-vs-signed-URL size limits. The description only restates the source options, adding no syntax or format detail beyond the schema. Baseline 3 is appropriate.

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 resource ('metadata index for any audio file') and enumerates the concrete outputs (content-type guess with confidence, brightness/dynamics buckets, dominant band, clipping/silence regions, tag suggestions), which lets an agent separate it from siblings like analyze_loudness or get_spectrum. It does not explicitly name the siblings it is not, so it stops short of a 5.

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?

'For triage or auto-tagging a library' implies the use case but gives no when-not guidance and never references the alternative tools in the sibling set. The agent must infer that this is the broad triage tool rather than a targeted analysis tool.

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