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

Annotations already declare readOnly/idempotent/non-destructive/openWorld, and the description adds substantial context beyond them: 200-account listing cap, zero balances only counted, labels from a fixed mint table, 422 pre-payment vs 503 RPC failure (neither charged), 0.5-3s latency, price and free-tier limits, and an untrusted-data warning. This is unusually rich behavioral disclosure.

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?

Front-loads purpose and the sibling-routing rule, then moves to return semantics, errors, timing and pricing in a logical order. Dense but nearly every clause carries operational value; the pricing/free-tier and docs-link tail is slightly over-packed for one paragraph.

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?

Covers network, commitment level, return semantics (200-account cap, zero-balance counting, label source), error codes with billing implications, latency and cost. Despite an output schema existing, the description supplies every operational detail needed to call it correctly.

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?

Single parameter with 100% schema description coverage, so the schema already documents the base58 owner address fully. The description adds no syntax or format detail beyond what the schema provides, matching the baseline 3 for high-coverage schemas.

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?

States a specific verb and resource ('Get the SPL token balances of a Solana wallet') and explicitly distinguishes itself from siblings, routing SOL to get_solana_balance and EVM tokens to get_portfolio. An agent can select it without opening any schema.

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?

Gives explicit when-to-use routing ('For SOL use get_solana_balance; for EVM tokens use get_portfolio'), plus the network/commitment context (Solana mainnet, confirmed). Nothing about which tool to pick for a given asset class is left to inference.

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