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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so safety is covered. The description adds real behavioral context beyond that: results are filtered to entries that actually have a playable channel, and a count is included. It does not describe ordering or whether the list is exhaustive, so it falls 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?

A single sentence with zero filler, and the most decision-relevant token (the resource being listed) is front-loaded. Nothing repeats the title or annotations.

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 parameterless enumeration tool this is close to adequate, and the 'with the count' phrase partially compensates for the absent output schema. However, with no output schema the description should say what fields each entry carries (e.g. network id, broadcaster name) so an agent knows how to feed results into downstream calls like get_channel or search_channels. That gap keeps it at minimum-viable.

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 takes zero parameters, so per the rubric the baseline is 4. There is no parameter surface for the description to compensate for, and nothing in the text contradicts the empty 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?

The description names the exact resource returned (networks and broadcasters) and adds a meaningful qualifier, only those with a playable channel, plus the count. That distinguishes it from the sibling list_* tools (list_cities, list_languages, list_tags) without needing to open the schema. The verb 'list' is implied by the name rather than stated, which keeps it just 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?

There is no guidance on when to call this versus alternatives such as search_channels, get_channel, or list_cities. The 'playable channel' qualifier hints at a discovery/browse use case, but nothing states the condition under which an agent should prefer this tool. Usage must be inferred entirely.

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