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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds meaningful context beyond that: the data source (DeFiLlama), the exact return fields, and a concrete example response, which is valuable since there is no output schema. It omits any rate-limit or freshness caveats, so not a full 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 purpose line followed by clearly labeled 'Use when', 'Not for', 'Returns', and an example — every section earns its place. The embedded example JSON and the '$0.000 USDC per call' line add mild bulk without much utility, keeping it short of a 5.

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 correctly carries the return contract by listing tvl/change_1h/change_1d/change_7d/chains[]/category and a sample payload. Combined with the usage routing, an agent has what it needs; minor gaps like pagination or data staleness keep it from 5.

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 'protocol' param already documents accepted names/slugs and the empty-string-equals-top-10 behavior. The description's example names and 'leave empty' semantics largely duplicate the schema, so baseline 3 is appropriate.

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 ('DeFi protocol Total Value Locked from DeFiLlama') and clarifies the two retrieval modes (top 10 or a named protocol). It explicitly distinguishes itself from yield_scanner and dune_query, so an agent can separate it from siblings without reading another 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?

Provides explicit 'Use when' conditions and a 'Not for' block that routes the agent to named alternatives (yield_scanner for yields, dune_query for revenue/custom metrics). This is textbook when/when-not/alternative guidance.

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