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

The readOnlyHint annotation already conveys that this is a safe read operation. The description adds useful behavioral context beyond annotations: the tool is v4-only, operates protocol-wide across chains, and returns samples over a time window. It does not fully describe output shape or sampling semantics, but with annotations covering the safety profile this is a minor gap.

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 with no redundancy: the first establishes scope, the second gives a key operational detail, and the third provides usage guidance with sibling references. Everything present earns its 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 read-only historical data tool with optional parameters and no output schema, the description is complete enough. It covers what data is returned, how to scope it across chains, what the data is useful for, and what it should not be used for. No critical context is missing.

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%, so the schema already documents window, chainId, and version. The description adds context about chainId omission and v4-only behavior, but most parameter meaning is already present in the schema. This is the baseline 3 case where the schema carries the parameter documentation load.

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 uses specific language: 'Aave v4 protocol-wide history' with concrete metrics (market size, total borrows, available liquidity). It explicitly distinguishes itself from get_user_summary_history and get_apy_history, making its scope clear relative to siblings.

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 states exactly when to use the tool ('is the protocol growing') and provides explicit exclusions with named alternative tools: not for a single wallet (get_user_summary_history) or a single reserve (get_apy_history). It also gives operational guidance on omitting chainId for all-chain coverage.

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