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

Annotations declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, but the description adds valuable behavioral detail: it 'reads straight from each chain's RPC' (network access), performs parallel checks on all chains, and returns only active chains. It also discloses pricing ($0.002 per call, 10 free/day), which is a cost implication not covered by annotations. No contradictions with 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?

The description is a single, information-dense sentence that front-loads the core purpose and data returned, then details the chain="all" behavior and pricing. It wastes no words but is slightly long; however, every clause adds value. The structure flows logically from function to usage nuance to cost.

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?

Given there is no output schema, the description clearly lists the return items (balance with USD, transaction count, contract/wallet status, ENS name). It also covers usage nuances (all vs. specific chain) and cost. It omits error handling or rate limits, but for a read-only lookup with strong annotations, this is adequate. The main missing piece is a note on address format validation, though the schema's pattern covers that.

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?

With 0% schema description coverage, the description must explain parameters. It explains 'chain' thoroughly: '17 EVM chains at once or one chain' and the specific behavior of chain="all" (parallel checks, returns only active chains). The 'address' parameter is implicit from context (the target of the lookup) and the schema's regex pattern. It does not enumerate the chain list, but the enum covers that. This compensates well for the coverage gap.

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?

The description clearly states the tool's function: 'Native balance (with USD), transaction count, contract or wallet, ENS name — for any address on 17 EVM chains at once or one chain.' It names the specific data returned and the resource (EVM address), distinguishing it from siblings like ens_resolve (ENS-only), evm_tx (transactions), and evm_token_security (security checks). The scope (17 chains) and the dual mode (all or one) are explicit.

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?

The description explains the key usage decision: 'chain="all" checks every supported chain in parallel and returns only where the address has balance, transactions or code — the quick "where is this wallet active" answer.' This clarifies when to use the default all-mode versus a specific chain. However, it does not explicitly mention alternatives (e.g., ens_resolve for ENS-only) or when NOT to use this tool, though the sibling context makes it inferable.

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