whale_activity

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

Annotations already declare readOnly, idempotent, openWorld, and non-destructive, so the safety profile is covered. The description adds real value beyond that: 'Ethereum ERC-20 transfers only' scopes the data source, and 'no API key, nothing signed or spent. Fails with an error message on an unknown symbol or an unreachable upstream source' discloses auth and failure behavior. Only the lack of rate-limit or freshness-window detail keeps it from a 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 followed by scannable Use when / Not for / Returns / Example / Price blocks — every section is labeled and easy to parse. The full JSON example response is somewhat long, but it demonstrates the shape of large_transfers[] and is defensible for a tool with no output schema.

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 compensates by enumerating return fields (from, to, amount, usd_value, minutes_ago, total_volume_usd) and giving a concrete example. Combined with the Ethereum-only scope and documented failure modes, an agent has everything needed to call and interpret this tool.

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 both parameters are already documented in the schema, establishing a baseline of 3. The description's 'large wallet movements' hints at the min_usd threshold but never explains its default or units, so it adds essentially nothing over the schema.

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 and resource — 'Detect recent large wallet movements for a token' — with the parenthetical 'whale tracking' anchoring the concept. An agent can distinguish this from token_price, wallet_balance, or orderbook_depth without opening any 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?

Explicit 'Use when' and 'Not for' clauses name two concrete alternatives (wallet_balance for address holdings, orderbook_depth for exchange book size) and give the discriminating condition for each. This is exactly the when/when-not/alternatives structure that earns the top score.

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