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

Adds useful context beyond readOnlyHint: the operation is public with no key needed, and it returns live count, nicknames, and status values. It does not cover edge cases such as empty channels, rate limits, or nickname visibility, but it is solid for a read-only tool.

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-loads what the tool returns, then auth posture, then the recommended use case. Three compact sentences with no wasted text.

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 one fully documented parameter, readOnly annotations, and no output schema, the description supplies what an agent needs: return fields, public access, and intended decision context.

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 schema fully documents the single domain parameter, including the bare-domain versus full-URL room distinction. The description itself adds no parameter-level detail beyond saying 'a domain's mURL channel,' so the schema carries the parameter semantics.

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 presence-check operation on a domain's mURL channel, including what it returns: live participant count, roster nicknames, and channel status. This clearly distinguishes it from content-oriented siblings such as mURL_read_channel and channel-enumeration siblings such as mURL_list_channels.

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?

Gives a clear use case: gauge whether a domain has an active audience before posting. It does not explicitly name alternatives or when-not-to-use conditions, so it falls short of full routing guidance.

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