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

Annotations already declare readOnlyHint=true and destructiveHint=false, and the description reinforces that with 'reads or computes only and changes nothing'. It goes further by disclosing error behavior (malformed address rejected with 400 and uncharged), pricing model ($0.01/call, first 25 free, failed calls free) and that repeats are billed — which usefully explains why idempotentHint is false.

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 purpose and unit, then routing to siblings, then error/pricing behavior. Dense but each sentence carries information; the pricing and free-tier details are slightly verbose for a balance lookup, keeping it just short of a 5.

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?

No output schema exists, yet the description specifies the return values (wei and CELO) and the block context (latest). Combined with error handling, billing, and sibling routing, an agent has everything needed to call this correctly on the first attempt.

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?

Only one parameter and schema description coverage is 100%, so the schema already documents the address field as a '0x wallet or contract address'. The description adds a worked example address and the note that any 0x address works, which is marginal value beyond the schema. Baseline 3 applies when the schema does the heavy lifting.

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 ('Native CELO balance ... of any 0x wallet address on Celo at the latest block'), gives the underlying RPC (eth_getBalance) and the return units (wei and CELO). It also explicitly distinguishes itself from celo_token_balance and wallet_portfolio, so an agent can select it 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?

Gives a concrete use case ('check whether a wallet can pay gas or a transfer') and names both alternatives with the condition that selects them: celo_token_balance for ERC-20s, wallet_portfolio for all holdings at once. Nothing about when-to-use is left to inference.

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