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

Annotations cover the safety profile (readOnly, idempotent, non-destructive, openWorld), so the bar is lower. The description still adds valuable non-schema behavior: it says it reports existence and prices account creation, and discloses the paywall (25 free calls/day then $0.01 USDC via x402) — a real constraint the agent cannot see in 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?

Dense but front-loaded: the imperative 'Run before sending a token' and the ATA explanation come first, then example, then cost. The trailing 'Outputs explained: GET /api/tools/token_account' is slightly awkward and reads like a docs pointer rather than a sentence, but nothing is wasted.

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?

There is no output schema, and the description compensates by stating what the call reports (existence and creation cost), plus the routing rationale and pricing. It points to an external endpoint for output details instead of describing return shape inline, which is a minor gap for a read tool with no output schema.

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%, so the baseline would be 3. The description earns above baseline by reinforcing the non-obvious semantic that wallet is the owner/recipient and token must be an address rather than a ticker, plus a worked example showing a USDC lookup end to end.

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: 'Finds the token account (ATA) for a wallet and token with the token's real program, says if it exists, and prices creating it.' It also distinguishes itself from siblings by naming find_token and tokens as the source of the token address, so an agent knows where token_account sits in the flow.

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?

Gives explicit when-to-use guidance ('Run before sending a token') and explains the underlying reason tokens go to an ATA, not the wallet. It stops short of naming when NOT to use it or listing a sibling alternative for the same job, but the trigger condition is unambiguous.

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