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

Goes well beyond the readOnly/openWorld annotations by disclosing the full access/payment model: subscription path, x402 pay-per-call path, and the exact failure mode (returns a PaymentRequired object with no data when neither is available). This is the kind of behavioral context an agent needs before invoking.

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?

Front-loaded with the purpose and return contents, then the access/payment behavior, which is the right ordering. Slightly redundant, as 'recomputed on the intraday board' and 'Live intraday version' restate the same idea, but nothing is wasted overall.

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 compensates by describing what comes back (top 10 per book, live awareness block with sector money flows, coil setups with coil_score, coverage) and fully covers the auth/payment prerequisites and error behavior. Nothing needed to call it correctly is missing.

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?

Zero parameters, so there is nothing to document and the schema is trivially complete. The baseline for a no-parameter tool is 4; the description correctly adds no spurious parameter detail.

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+resource: top 10 leadership names per book (US stocks, ETFs, crypto coins) ranked by opportunity score and recomputed on the intraday board. The 'live' scope plus the named output contents (sector money flows, coiled setups with coil_score, coverage) clearly distinguish it from the non-live sibling get_market_leaders.

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?

Explicitly frames itself as the 'Live intraday version' and lays out the conditions to get data: a Coil Live subscription (7-day trial), connecting the connector and signing in, or an x402 wallet for per-call payment. It doesn't explicitly name get_market_leaders as the non-live alternative, but the live-vs-static distinction is clear from context.

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