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

With no annotations provided, the description carries the full burden of behavioral disclosure, and it excels. It details live data sources (deepest USDC pool, last Raindex fill), corrections (ERC-4626 wrapper rate), additional outputs (market session, leg age, pool depth, cross-issuer pool, one-sentence read), error behavior (404 for unknown ticker, no charge), and pricing ($0.02 via x402). This is comprehensive and leaves little ambiguity about what happens when the tool is invoked.

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 description is a single dense paragraph, but every clause serves a purpose. It front-loads the trigger condition, then enumerates the computation and outputs efficiently. While it is longer than some, the information density is high and there is no fluff. It earns a 4 for being appropriately structured and informative without excessive verbosity.

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?

Given the tool's complexity (multiple data sources, adjustments, and a rich set of outputs) and the absence of an output schema, the description provides a thorough account of what the agent will receive: premium/discount in bps, session, age, depth, cross-issuer info, and a one-sentence read. It also covers cost, payment rail, and error cases. Nothing essential is missing for correct invocation and expectation setting.

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 description coverage is 100%: the schema already documents the ticker parameter with allowed forms (stock ticker, ST0x symbol, Coinbase symbol) and examples. The tool description adds minor illustrative examples ('wtAAPL, FGI') but does not introduce new meaning beyond the schema. Since the schema fully documents the parameter, the baseline of 3 applies; the added examples are marginal and do not push it higher.

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 states a precise purpose: determine whether an ST0x tokenized stock trades above or below the real share, returning a premium/discount in basis points. It specifies the resource (ST0x on Base) and clearly differentiates from siblings like st0x_pulse (likely a market snapshot) and st0x_registry (likely a listing tool). The verb 'send' and expected output give unambiguous intent.

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?

The description opens with an explicit trigger: 'Use this when the question is whether an ST0x tokenized stock on Base trades above or below the real share.' This is a clear when-to-use statement. However, it does not explicitly mention when not to use it or name alternative tools, though the sibling list implies some are related. The cost and error handling are noted, but the exclusion guidance is absent, so it falls short of a 5.

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