explorer_get_historical_balance

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

Annotations already declare readOnlyHint=true and openWorldHint=true. The description is consistent and adds the specificity of historical block scoping, but it does not disclose additional behavioral details such as return format (e.g., wei vs ETH), error handling for invalid blocks, or any rate limits. Thus it meets the baseline but adds limited extra transparency.

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?

A single sentence of 14 words is exceptionally concise and fully front-loaded with the core action. Every word earns its place, meeting the gold standard for conciseness.

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 the tool's simplicity (3 all-required params, no nested objects) and the annotations covering safety, the description is largely complete. It clarifies the purpose and all parameters are documented. However, with no output schema, it would be slightly more complete if it mentioned the return unit (e.g., wei), but this is a minor gap.

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 input schema already provides 100% parameter coverage, with each parameter described (chainId, address, blockNumber). The description does not add any parameter information beyond the schema, so it earns the baseline score for high schema coverage.

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 uses a specific verb ('Get'), names the exact resource ('native token balance of an address'), and scopes it to 'a specific historical block number.' This clearly distinguishes it from sibling tools like explorer_get_historical_token_balance (which handles token balances) and evm_get_balance (which is for current balances).

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 clearly implies when to use this tool: when a historical native token balance is needed. However, it does not explicitly name alternatives or state when not to use it, so it stops short of full guidance.

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