An agent's built-in wallet, or the signer wallet, with balance

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

With readOnlyHint: true already in annotations, the bar is lower, and the description adds genuine value on top: the mainnet-specific behavior (reporting $THREE balance and deploy-fee tier) and the derivation mechanism (Metaplex Core Asset Signer PDA). The closing 'Read-only; never moves funds' reinforces the annotation rather than contradicting it, which is appropriate emphasis for a financial read operation.

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 front-loaded with the core purpose in the first sentence, then systematically walks through each mode. At ~135 words it's longer than ideal, but the three-mode structure and network-specific behavior justify the length. Every sentence serves a distinct purpose with zero filler.

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 tool with 3 optional params, 3 usage modes, and network-dependent behavior, the description is admirably complete. It covers the default behavior, the derivation case, the raw address case, network-specific output, and points to `three_status` for more details. Minor gaps: no mention of what happens when both `asset` and `address` are passed, and the output format isn't hinted at without an output schema.

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 baseline is 3, and the description goes beyond this: it explains the derivation behavior of `asset`, distinguishes it from `address`, and documents the default when neither is passed (configured signing wallet). The semantics around parameter precedence and meaning are materially enhanced.

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?

"Show a wallet address and its live SOL balance" is a specific verb+resource statement that clearly distinguishes this from siblings like `send_signed_transaction` and `prepare_agent_mint`. The three explicit invocation modes (asset, address, neither) map directly to the params, making the tool's role unmistakable.

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 embeds a concrete workflow example: "confirm it is funded before mint_onchain_agent", which tells agents when this is the right tool in their task sequence. It also cross-references `three_status` for the deploy-fee tier info. It stops short of naming explicit alternative tools or saying 'use X instead', so it gets a 4 rather than a 5.

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