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

The description adds behavioral detail beyond the readOnlyHint annotation by stating that 'Historical and fee fields fail open when DeFiLlama does not cover a chain.' This discloses important fallback behavior that the annotation does not convey, providing meaningful transparency.

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 three sentences, front-loads the core purpose, then gives usage guidance, and ends with a caveat. Every sentence earns its place with no fluff or redundancy.

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 moderate complexity, the presence of an output schema, and readOnlyHint annotation, the description is complete. It covers purpose, usage patterns, default behavior (highest-TVL), and a key edge case (fail-open), leaving no major gaps.

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 100%, so the schema already explains each parameter. The description adds value by illustrating usage of the chains parameter with an example and clarifying the limit behavior ('omit chains to inspect the highest-TVL ecosystems'). However, it doesn't add detail about the days parameter, so a baseline of 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?

The description starts with a specific verb and resource: 'Compare blockchain ecosystem health using DeFiLlama current TVL, 7-day and 30-day TVL changes, and aggregate fee activity.' This clearly distinguishes it from sibling tools like get_protocol_tvl or get_dex_volume, which focus on different metrics.

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 provides clear usage contexts: 'Pass chains such as [...] for a focused comparison, or omit chains to inspect the highest-TVL ecosystems.' While it doesn't explicitly name alternatives or exclusion cases, it effectively communicates when and how to use the tool, earning a 4 rather than a 5.

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