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

Annotations already cover read-only, idempotent, and non-destructive behavior. The description adds useful context beyond that: the 365-day history limit, the 7/30/90-day change stats, and the fact that the tool is free. No contradiction with annotations.

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?

Three short, information-dense sentences. The main purpose is front-loaded, followed by mode-specific details and pricing. No filler or redundant elaboration.

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 carries the return-value burden and does convey the two output shapes: ranking with token symbols, or daily history with change stats. It does not spell out the exact structure of history entries or the meaning of 'limit', but for an optional-parameter read-only tool this is largely sufficient.

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 only 33%, and the description compensates by explaining that 'chain' switches between ranking and history modes. It also restates the days bound. However, 'limit' is left semantically unexplained in both the schema and description, so one parameter remains opaque.

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 clearly states what the tool does: it returns TVL rankings for all blockchains or daily TVL history for a single chain. It explicitly differentiates the two modes by the 'chain' parameter and is distinguishable from sibling tools like crypto_price or defi_protocol.

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 gives clear context on when to include the 'chain' parameter versus when to omit it, effectively instructing the agent on mode selection. It does not explicitly name alternative sibling tools or state when not to use this tool, so it misses the top tier.

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