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

Goes well beyond the readOnly/openWorld/destructive annotations: discloses cost (5¢ per call), payment rail (x402, USDC on Base, no account), where payment headers live, and that the tool returns the exact settlement steps. This is exactly the kind of non-obvious behavioral context 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?

Cost and payment rail are front-loaded, then the output shape, then the sibling alternative. Dense but every sentence carries information; the payment-steps sentence is slightly circuitous but earns its place.

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?

For a zero-input paid read with an output schema present, the description covers everything an agent needs: cost, payment mechanism, what is returned (cited bullets with source URLs), and the free alternative. Nothing material 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 the schema is trivially complete; the description confirms 'no input required,' which is the only parameter fact an agent needs. Baseline 4 per the 0-param rule.

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 product (today's market-news brief) with a precise composition rule — synthesized published digest plus live market wire into a cited bullet list — and names its sibling market.pulse as the unsynthesized source. An agent can distinguish it from every sibling without opening a 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?

Explicitly states no input is required and names the free alternative (market.pulse) with the condition that selects it (un-synthesized raw material vs. synthesis). Lacks an explicit 'use this instead of X when...' phrasing, but the routing choice is clear.

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