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

The description goes well beyond the annotations by disclosing that invalid addresses return 400, that Base calls are not charged for invalid addresses while other rails may charge, the $0.04 x402 price with USDC on Base, the MCP payments constraint, and the buyer terms link. This is exactly the behavioral context an agent needs before invoking a paid read-only endpoint.

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 dense but front-loaded: purpose first, then payload, then payment and validation caveats. It is longer than a minimal description, but most of that length is earned by payment, error, and legal context; the terms URL and pricing detail could be tightened slightly.

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 paid, read-only portfolio endpoint with no output schema, the description covers the return fields, concentration scoring, validation behavior, pricing, payment rails, and legal terms. An agent has enough to call it correctly and understand the cost and failure modes.

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 coverage is 100% for the single `address` parameter, so the baseline is 3. The description adds useful validation detail ('0x...', 40 hex) and confirms the address is snapshotted across Base and Ethereum, which adds meaning beyond the schema.

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/resource: a wallet balance and portfolio API for one EVM address on Base and Ethereum, naming the assets covered and the JSON payload returned. It is very clear what the tool does, but it does not explicitly distinguish itself from the sibling `balance` tool.

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?

It gives some operational guidance (GET with an address, read-only, not advice) and payment rails, but it does not say when an agent should use this portfolio tool versus the sibling `balance` tool. Usage is implied rather than explicitly routed.

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