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

Annotations already declare readOnly, idempotent, non-destructive, and closed-world, so the safety profile is covered. The description adds behavior the annotations cannot: the listen link tunes in live and listeners don't pick an episode, and slots between episodes are reported as community bulletins. That edge-case disclosure is exactly the kind of context annotations can't carry.

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?

One long sentence, but it is front-loaded with the core action and then lists the returned fields, with the caveats last. Every clause carries information; the only cost is density — a reader scanning quickly has to parse a comma chain to find the scope rule.

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 fully carries the burden of explaining what comes back, and it does so field by field, including the live-tuning semantics of the listen link and the bulletin edge case. For a single optional-parameter, side-effect-free read, nothing essential is missing.

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 the station parameter already documents accepted forms (name, slug, id) with a pointer to list_stations. The description nevertheless adds meaning the schema does not: that omitting the parameter means querying every station rather than erroring or defaulting. That single fact is materially useful even at 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?

The description names a concrete query ("What's playing right now") and enumerates the payload: show/episode title, elapsed time, time remaining, episode page, support link, cover art, listen link. That is specific enough to distinguish a current-state query from a forward-looking one, but it never names a sibling such as whats_next or find_on_now, so differentiation is left implicit.

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?

It does state the key routing rule — pass a station for one station, omit it to get every station — which is genuine when-to-use guidance for the parameter. It says nothing about when to prefer a sibling over this tool, for example how it relates to find_on_now or whats_next, so the guidance is partial.

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