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

Annotations already declare readOnlyHint=true and destructiveHint=false, but the description adds significant behavioral context beyond that: zero balances are omitted, Solana SOL shown is spendable lamports (rent locked in token accounts excluded), and specific fee/rent thresholds that affect interpretation. This is exactly the kind of behavior an agent needs to know and it goes well beyond the annotation baseline.

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 longer than average, but every sentence carries essential operational information. It is front-loaded with the core purpose and usage directive, then dives into Solana-specific details that are critical for correct invocation. No filler or repetition, though one could argue the Solana details are dense and might be condensed. Still, it earns its length.

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?

For a balance-check tool with no output schema, the description fully compensates by explaining return behavior (zero balances omitted), the meaning of values on different chains, and the fee/rent constraints that affect subsequent calls. It covers all information an agent needs to correctly interpret results and decide whether to proceed with connect_drop. Very complete.

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 single parameter chainId is already fully documented in the schema with 'EVM chain ID or 1399811149 for Solana mainnet (Smart Send)', so schema coverage is 100%. The description does not add any new detail about the parameter itself; it only uses the chainId value in context. The baseline of 3 applies because the schema handles the parameter semantics completely.

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 opens with a clear verb and resource: 'Get native and token balances for the API key owner Smart Send embedded wallet on a chain.' It explicitly positions the tool as a pre-flight check for connect_drop, which distinguishes it from the sibling tools like connect_drop and connect_get_chains. The agent immediately knows what this tool does and how it relates to the drop operation.

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 first sentence includes the explicit directive 'Always call before connect_drop,' telling the agent exactly when to use this tool. It also provides situational guidance for both EVM and Solana paths, including when recipient accounts need extra SOL for rent. This is clear, actionable usage guidance with no ambiguity.

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