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

No annotations are provided, so the description carries the full burden. It usefully discloses that the call is 'Free' (implying no cost/credit consumption, unlike siblings), but says nothing about auth requirements, rate limits, or read-only semantics beyond the verb '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 sentences, zero filler, with the sequencing advice ('call this first') front-loaded after the content summary. Every clause earns its place.

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 output schema, the description does the work of describing return content by naming symbols, intervals and data source. That is enough for an agent to know what it will get, though it does not describe the shape or format of the returned data.

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 there is nothing to document; the baseline of 4 applies. The description correctly does not invent parameter discussion for an argument-less tool.

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?

Specific verb ('List') plus resource ('markets') and it enumerates what the listing contains: supported symbols, intervals and data source. An agent can immediately distinguish this discovery tool from the data-fetching siblings (get_kline, get_signal, backtest_signal).

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 an explicit sequencing directive — 'call this first to discover what is available' — which is exactly the guidance needed for a zero-argument discovery tool. It stops short of naming a specific alternative or a when-not condition, so it is clear context rather than full routing.

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