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

Annotations already declare read-only, open-world, non-destructive, non-idempotent, so the safety profile is covered. The description adds genuinely valuable behavior beyond that: it explains the WebSocket open/read/disconnect mechanism, warns it costs a few seconds, and discloses that the returned set is partial — none of which the annotations convey.

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?

Three tight sentences with zero filler: purpose, mechanism/cost caveat, and the partial-set caveat plus next-step pointer all front-loaded in useful order.

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?

Output schema exists so return values need no explanation; annotations cover safety. Combined with the latency and partial-snapshot caveats, an agent has everything needed to call this correctly and interpret the result.

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?

Schema description coverage is 100%, so all four parameters (limit, sport, search, in_play) are already documented with defaults and formats. The description adds no parameter-level detail, so the baseline 3 applies.

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 verb and resource with scope: 'List the events that currently have live prices.' It also discloses the non-obvious mechanism (WebSocket snapshot) and routes to the sibling list_event_offers, so an agent can distinguish it from other list_* tools without opening schemas.

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 clear context: the snapshot is not the full fixture list, only events currently priced, and directs the agent to pair the returned sport/event_id with list_event_offers. It stops short of explicit when-not-to-use guidance, but the partial-coverage warning effectively tells the agent what this tool is not for.

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