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

With no annotations, the description carries full burden. It discloses that the tool returns real-time data (current and next track, listeners) and that it's about a live web radio. It doesn't mention potential side effects, auth needs, or rate limits, but for a read-only tool with no side effects, this is adequate.

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?

The description is two sentences with no wasted words. The first sentence lists the outputs, the second provides usage context. It is front-loaded and every sentence serves a purpose.

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 tool with no output schema, the description fully explains the return values: current music, next music, connected listeners, stream link, and how to listen. This is complete and sufficient for the agent to understand what to expect.

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?

The tool has zero parameters, and schema coverage is 100%. The description does not need to add parameter information since there are none. Baseline for 0 parameters is 4.

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 clearly states the tool returns current playing info on the school radio, including specific items like current song, next song, listeners, stream link, and instructions. It uses a specific verb 'Retorna' and resource 'o que está tocando AGORA', and distinguishes from siblings which are about other school resources.

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 explicitly says 'Use quando perguntarem sobre a rádio da escola, o que está no ar, ou como escutar', which provides clear context for when to use the tool. However, it does not mention when not to use or explicitly compare to siblings, but given no other radio-related siblings, this is sufficient.

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