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

Annotations already declare readOnlyHint=true, so the description adds value by disclosing the return format: 'per-asset APY snapshots and Compound utilization where available.' It also includes the caveat 'where available,' which clarifies behavior when data may be incomplete. No contradictions 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 sentences, each with a specific purpose: what it returns, return details, and a use-case example. No fluff or redundant information. Front-loaded with the primary action ('Get current on-chain lending supply/borrow rates').

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?

The tool has an output schema, so return values need not be explained, but the description still mentions APY snapshots and utilization, which helps. The description covers the protocols, chains, and a concrete use case, making it complete for a read-only list-style tool with well-documented parameters and annotations.

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% (all parameters have descriptions), so the baseline is 3. The description adds context about protocol and chain coverage ('Aave v3 reserves and Compound v3 markets on Ethereum or Base') but does not add meaning for the assets filter or chain_id beyond what the schema already provides. The description does not compensate for any parameter gaps because there are none.

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 specific verb ('Get') with a clear resource ('on-chain lending supply/borrow rates') and explicitly scopes it to 'expanded Aave v3 reserves and Compound v3 markets on Ethereum or Base.' It also distinguishes from siblings like get_yield_rates by emphasizing protocol-specific lending rates, not general yields.

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 indicates when to use this tool: 'Useful for protocol-specific stablecoin yield comparisons (e.g., USDC on Aave vs Compound).' This provides clear context, but it does not explicitly mention sibling tools as alternatives or state when NOT to use it. No exclusions are given.

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