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

Goes well beyond annotations by explaining the counterintuitive readOnlyHint=false: 'Reads or computes only; not marked read-only because each call is charged.' It also discloses billing mechanics ($0.003/call via x402 USDC or card key, first 25 free, failed calls free), which the annotations cannot convey.

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 with the resource and its contents, then usage, then cost. Two tight sentences with no filler; even the pricing clause carries information an agent needs to decide whether to call.

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?

Although there is no output schema, the description enumerates the returned facts (chain id, USDC contract, decimals, explorer, RPC, x402 identifier), so an agent knows exactly what it will get. Nothing needed to call it correctly 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?

The tool takes zero parameters and the schema is an empty object at 100% coverage, so the baseline is 4. There is nothing parameter-level for the description to add or omit.

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 resource (Base mainnet reference facts: chain id, USDC contract/decimals, explorer, RPC, x402 network id) and its use case. It is trivially distinguishable from the many chain-operation siblings (base_balance, base_tx, etc.) since it takes no parameters and returns static configuration data.

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?

Explicitly says 'Use to configure an x402 or Base client,' which is a clear context for invocation and implicitly excludes the transaction/query siblings. It does not name a specific alternative or state when NOT to call it, so it stops short of a 5.

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