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

Goes well beyond the readOnly/openWorld annotations: discloses the upstream source, that the feed carries no symbols, the 1e30 scaling convention, and a per-call pricing model with confirmation that failed calls are free. Cost/authorization behavior is unusually well surfaced.

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?

Four tight sentences, front-loaded with source and scope, then the non-obvious formatting caveat, then cost. No filler or repetition of the title.

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?

An output schema exists and the safety profile is in annotations, yet the description still supplies the two things that schema cannot convey well: missing symbol data and the 1e30 price scaling. Nothing needed to call it correctly is absent.

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 the schema contributes nothing and the baseline is 4. The description correctly implies the call needs no inputs.

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+resource+scope: GMX token prices on Arbitrum from the public api.gmx.io/prices feed. Clearly distinguishable from all sibling ecommerce/social tools, which cover no crypto price feeds at all.

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?

Implies usage through 'Use the address to match the token yourself', which tells the agent what to do with the result but not when to prefer this tool or what prerequisites apply. No explicit when-to-use or exclusions, so it is adequate but implicit.

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