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

The annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds minimal extra behavioral context beyond 'available' and 'filtering', and does not mention return shape or pagination details, but those are not contradicted by structured data.

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?

The description is one short sentence that conveys the core operation, resource, and an important scoping trait ('available'). There is no filler or repetition of schema details, and the most important information is front-loaded.

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 simple, read-only listing tool with fully documented parameters and no output schema, the description is reasonably complete: it says what the resource is, that it lists available markets, and that filtering is possible. It could be more complete by noting relationship to search_markets or return ordering, but nothing essential is missing for invoking it correctly.

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 input schema documents all four parameters with descriptions, and the schema coverage is 100%, so the baseline of 3 applies. The tool description only says 'optional filtering' and does not add parameter-specific semantics beyond what the schema already provides.

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 clearly identifies the verb ('List'), the resource ('prediction markets'), and the scoping concept ('available' plus filtering), so an agent can understand what the tool does. It is easy to distinguish from get_market, which targets a single market, but there is no explicit comparison to the sibling search_markets tool, so it stops 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?

The description implies its use case: browse or retrieve available prediction markets with optional filters. However, it does not state when to prefer this over search_markets, get_market, or other listing tools, and it provides no explicit exclusions.

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