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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered; the description adds the commercially important trait that each successful call costs $0.002 in USDC via x402 on Base/Solana/Arc and that failed calls are not charged. That is exactly the kind of cost/behavior detail annotations cannot express. It does not discuss data freshness or update cadence for the 'listed' status, which keeps it off 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?

Three dense sentences, front-loaded with the returned fields before the exclusions, sibling routing, and pricing. Every clause carries information, though the pricing sentence is appended abruptly and could be split for readability; nothing is redundant.

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 an output schema present, the description need not explain return shape, yet it still summarizes the fields, declares what is absent, names an alternative, and discloses cost — more than enough for a zero-parameter read tool. The only missing element is any hint about how current the vault listing data is.

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?

The tool takes zero parameters, so there is no schema surface for the description to compensate for; baseline 4 applies. The description correctly treats the call as a parameterless snapshot rather than implying filters that do not exist.

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?

Names a specific resource (GMX v2 GLV liquidity vaults on Arbitrum) and enumerates exactly what each record contains: vault name, vault token address, long/short collateral tokens, listed flag, listing date. It also distinguishes itself from the nearest sibling by naming crypto_balancer_v2_pools for a different need, so an agent can route 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?

Provides an explicit negative boundary ('Trader net exposure, vault APY and GM market composition are not in this response and are not reported'), which tells the agent when to look elsewhere, plus an explicit alternative for Balancer V2 pool data. It stops short of stating a positive trigger condition or prerequisites, but the scope and exclusions make the intended use unambiguous.

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