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

Annotations already declare readOnly, idempotent, non-destructive behavior, so the main added value is the entitlement gate and its discrete reason codes, plus the explicit note that the call is free. It does not describe latency, caching, or refresh cadence of the 'data freshness' field, which would be useful for an open-world status probe.

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 compact sentence with zero filler, and the content is front-loaded. The fragment style and placement of 'Call first' at the tail rather than the head make it marginally less scannable than it could be.

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 an output schema present and zero parameters, the description only needs to convey purpose and gating, which it does. The one soft gap is that 'ready layers' is unexplained jargon an agent may not be able to interpret.

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 no parameters, so there is nothing for the description to disambiguate and the baseline applies. The only caller-supplied context is auth/entitlement, which the description does address via the reason codes.

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 specific resource and enumerates the status dimensions returned: market session, data freshness, ready layers, and caller entitlement. That is clearly distinct from siblings like scan_market or get_scanner_matches, though the telegraphic phrasing ('Live Scanner now') is slightly cryptic on first read.

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?

'Call first' gives an explicit ordering instruction, and 'Free' signals there is no quota cost to checking. The reason codes (scanner_disabled, verify_email, pro_required) tell the agent what to do when access is denied. No alternative tools are named, so it stops short of full when/when-not guidance.

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