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

With no annotations, the description carries the full burden and does well: it discloses the 0.25% fee deducted from the amount, that the transaction is unsigned and must be signed/broadcast externally, and who pays the network fee in which token. It does not address what the unsigned transaction looks like when returned or whether authentication (the bearerToken parameter) is required.

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?

Three short sentences, each doing distinct work: purpose, fee/flow mechanics, alternative routing. Front-loaded with the core action and free of 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 fee-bearing, multi-party flow the description covers the economics, the signing step, and the sibling alternative, which is most of what an agent needs. The missing piece is what the tool actually returns (an unsigned transaction payload) and whether the bearerToken parameter is required for authenticated merchants.

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 75%, so the baseline is 3; the description adds real meaning by clarifying that 'amount' is debited from the sender and the recipient nets amount minus 0.25%. That fee arithmetic is not in the schema. The undocumented bearerToken parameter is left unaddressed.

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 first sentence states a specific verb and resource ('Build an unsigned USDC transfer'), plus the crucial modifier 'unsigned' that separates it from a broadcast tool. The final sentence names the sibling send_usdc and what distinguishes it, so an agent can choose without opening either 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?

It gives an explicit routing rule: use this when the sender pays the Solana network fee in SOL, use send_usdc when the fee should be paid in USDC. It also states the required follow-up ('The sender must sign and broadcast it'), which is the key precondition for using the output.

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