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

Annotations cover only safety (readOnly/idempotent/non-destructive), and the description layers on substantial operational context beyond them: freshness semantics (stale:true past a minute, rows up to 5 minutes old), Novig's feed-vs-polling variability, ProphetX sandbox caveat, and that paper trades are sandbox-only and never sent to the venues. This is exactly the extra behavioral detail the annotations cannot 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?

The purpose is front-loaded, but the body is a single dense run-on paragraph of semicolon-chained clauses that drifts into trade-routing and paper-trade behavior tangential to reading quotes. It is information-rich but poorly structured and not concise for the two-argument read it performs.

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, return values need not be spelled out, and the description nonetheless covers venue coverage, data freshness, and source caveats well. The only real gap is the undocumented `full` parameter, so an agent can call this correctly but not tune its verbosity.

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 coverage is only 50%: `ref` is documented in the schema, but `full` has no description and the tool description never explains what it does. The description instead spends its detail on output fields (yes_pct, as_of, last_trade_at), so it does not compensate for the undocumented parameter.

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 opening clause states a specific verb-plus-resource and scope: one instrument's YES price across every venue Arena shows, explicitly naming Kalshi, Novig, Polymarket and ProphetX and noting it is not ranked by price. That is enough for an agent to separate it from siblings like get_instrument, get_market and find_price_gaps without opening any schema.

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: the reader infers this is the tool for cross-venue comparison, and the note 'When cross_venue is false only Kalshi is listed' gives one conditional. There is no explicit when-to-use/when-not guidance and no routing to sibling tools such as get_instrument or find_price_gaps.

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