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

Annotations already declare readOnly/idempotent/openWorld/non-destructive, so the safety profile is covered. The description adds genuine behavioral context beyond structured fields: the upstream source (DeFiLlama), the coverage set ('and more'), and the specific 0.5% deviation rule that produces a depeg signal. It doesn't discuss freshness/latency beyond 'real-time' or error behavior, keeping it short of a 5.

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 purpose and return shape before the trigger examples. The four example queries are slightly verbose but each demonstrates a distinct query pattern the tool answers, so they largely earn their 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 single-optional-param read tool with a full output schema and complete annotations, the description covers what the data is, where it comes from, the fields returned, and the depeg threshold. Nothing needed to call it correctly is missing, and return-shape detail is left to the output schema.

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% and the single optional `symbol` parameter is already fully documented (case-insensitive, omit for all). The description adds no syntax or format detail beyond what the schema provides, so the baseline 3 applies.

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 ('Returns real-time USD peg data for the top stablecoins'), names concrete coins, the data source (DeFiLlama), and the exact fields returned (price, deviation, market cap). An agent can distinguish this from every sibling (health factor, utilization, wallet scans) purely from the description.

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 says 'Use this when asked:' and follows with four concrete trigger queries covering both single-coin ('What is DAI trading at?') and market-wide ('Which stablecoins are showing depeg signals right now?') use cases. Sibling tools are unrelated domains, so no exclusion routing is needed; the trigger set is unambiguous.

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