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

Annotations only declare readOnlyHint and openWorldHint; the description adds genuinely useful non-obvious behavior: a per-call price ($0.005 USDC via x402) and a payment URL. It also enumerates the return contents (sentence, action type, net asset changes, fee). It does not cover failure modes such as unsupported chain or unparseable hash, which keeps it at 4.

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 tight paragraph, front-loaded with what the tool does and immediately followed by the return contract and pricing. Every clause carries information; only the trailing URL/price block is slightly dense, but it is operationally necessary.

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?

With no output schema, the description correctly assumes the burden of describing return values and does so concretely (one-sentence explanation, action type enum-like list, net asset changes, fee). Payment semantics are left to the schema. Only error/edge-case behavior is unaddressed.

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%, so the schema already documents both parameters and the baseline is 3. The description adds meaning beyond the schema by noting chain auto-detection (i.e. the agent must not supply a chain) and by framing the paid-per-call model that governs the optional payment parameter.

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 (explain), resource (Solana/Base transaction), and the exact output shape with a concrete example ('Wallet X swapped 0.5 SOL for 1,203,442 BONK on Jupiter'). This clearly separates it from siblings like solana_transaction or base_transaction, which fetch raw transaction data rather than a natural-language summary.

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?

'Paste any Solana signature or Base tx hash' tells the agent exactly what input triggers the tool, and 'Chain auto-detected' removes a decision the agent might otherwise agonize over. It does not explicitly say when to prefer this over raw transaction-lookup siblings, so it stops short of a 5.

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