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

Annotations only cover readOnly/openWorld, but the description adds critical operational behavior: a $0.10 USDC x402 price on Base mainnet, that an unpaid call returns a PaymentRequired challenge, and the exact retry mechanic (re-send with signed payload in _meta["x402/payment"]). This is behavior an agent cannot infer from structured fields and would otherwise discover by failing.

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-loads the deliverable and its contents, then the cost/payment mechanic in two compact sentences. Dense with zero filler; every clause carries either scope or an actionable payment instruction.

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 enumerating the returned fields, and it covers the non-obvious x402 payment path. The only gap is it doesn't clarify how the configurable 'period' interacts with the '30-day' framing, but overall an agent has enough to call 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?

Schema coverage is 100% with both params documented, so the schema does the heavy lifting and a 3 is the baseline. The description implies a 30-day window but does not clarify that the 'period' parameter can override it, leaving a small mismatch between the fixed '30-day' framing and the configurable 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?

States a specific verb+resource ('Complete 30-day threat brief for an industrial sector') and enumerates the exact payload (actors, CVE counts, campaigns, advisories, trend, top 3 actions), so an agent knows precisely what it produces. It also positions itself against the broad family with 'One call replaces 5+ chained calls.'

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?

'One call replaces 5+ chained calls' gives a clear usage signal: reach for this instead of composing several narrower lookups. It stops short of naming a specific alternative (e.g., getSectorSitrep or getSectorDelta) or stating when not to use it, so no explicit exclusions.

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