List marketplaces

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is largely covered. The description adds one genuine behavioral trait not in annotations — 'Never billed' — but the phrase is cryptic (does it mean accessing this list is free, or that these marketplaces never incur capture charges?). It says nothing about return format or stability of the list.

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?

Two short, front-loaded fragments with no filler. The trailing 'Never billed.' is terse to the point of ambiguity, which slightly undercuts clarity, but nothing is wasted.

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 parameters and no output schema, the description carries the burden of describing what comes back, and it does so only loosely ('marketplaces ... and the hosts that route to each'). The ambiguous pricing remark leaves an agent unsure what 'billed' refers to. Adequate but with clear gaps for a reference-data tool.

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 the baseline of 4 applies; the description need not explain any inputs and correctly does not.

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 the resource clearly: marketplaces and the hosts that route to each, with the qualifier that these are the ones Tickets.dev can capture. That is a specific and understandable scope. No sibling (find_events, get_listings, compare_prices, get_seat_map) is similar enough to need an explicit distinction, though naming it as a discovery/reference lookup would sharpen it.

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?

Usage is only implied — an agent is expected to infer that this is a static reference lookup to run when it needs the supported marketplace/host universe. There is no explicit 'use when' statement, no mention of when not to call it, and no routing to alternates (though no real alternate exists for this resource).

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