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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context: it lists the asset types included (fungible tokens, regular + compressed NFTs), the standard used (DAS), and the fields returned (name, symbol, balance, interface type). It doesn't mention pagination or rate limits, but for a read-only list tool this is adequate.

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 followed by a concrete example. Every clause earns its place: the resource, the asset types, the standard, the return fields, and the example call. No fluff, no repetition of the schema.

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 read-only list tool with 2 fully-documented parameters and no output schema, the description is nearly complete. It covers what the tool returns (name, symbol, balance, interface type) and what it operates on (wallet address). The only gaps are pagination behavior and whether the response is a flat list or grouped, but these are minor for a tool of this simplicity.

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?

Schema description coverage is 100%, so the schema already documents both parameters (address and _apiKey) with descriptions. The description adds a concrete example with a real-looking address and API key placeholder, which helps an agent understand the expected format. However, it doesn't add meaning beyond what the schema provides — baseline 3 is appropriate.

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 states a specific verb ('lists'), a clear resource ('every digital asset... held by an address'), and the exact scope (fungible tokens, regular + compressed NFTs via DAS). It also includes a concrete example call, which makes the tool's purpose unmistakable. It distinguishes itself from siblings like helius_asset (singular asset) and helius_parsed_transactions (transactions, not holdings).

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 you need all assets owned by a Solana wallet. It doesn't explicitly name alternatives or exclusions, but the sibling context (helius_asset for a single asset, helius_parsed_transactions for transaction history) makes the usage context clear. A brief 'use helius_asset for a single asset' would push this to 5.

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