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

Annotations already declare readOnly, openWorld, idempotent=false, destructive=false, but the description adds critical context beyond them: the payment/auth model (subscription or x402 wallet) and the exact failure behavior (returns a PaymentRequired object with no data when neither is present). That failure-mode disclosure is exactly the kind of trait an agent needs before calling.

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?

It is front-loaded with what the payload contains before pivoting to access requirements, which is the right ordering. The subscription sentence is slightly wordy ('connect the Coil Live connector and sign in') but every sentence carries information an agent needs.

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 must convey returns, and it does list the included sections (regime, candidates, movers, crypto gate, awareness read with leaders, money flows, coiled setups, coverage) plus the error shape. Enough to call correctly, though it doesn't describe payload shape or freshness/latency details.

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 per the rubric the baseline is 4. The description correctly adds no parameter guidance because there is nothing to configure.

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 names a specific verb (get) and enumerates the payload contents (regime, top-5 candidates, movers, crypto gate, awareness read), and labels it the 'Live intraday version,' which separates it from the non-live sibling get_morning_brief. Differentiation is implied rather than explicitly naming the sibling, so it falls 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?

It gives clear access prerequisites: a Coil Live subscription (7-day trial) with connector sign-in, or an x402 wallet for per-call payment. It stops short of explicitly routing agents to get_morning_brief when they want end-of-day rather than live data, so the alternative-selection guidance is only implied.

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