send_to_username

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

Without annotations, the description carries the burden. It discloses useful traits: the tool looks up the recipient's wallet and performs an intraledger transfer (free, instant). However, it does not mention that funds will be deducted from the sender's wallet, that the operation is irreversible, or that authorization is required. These are significant gaps for a payment tool.

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 two sentences, front-loaded with the primary action, and adds one key benefit (intraledger, free, instant). No wasted words.

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?

The description is adequate for basic selection but incomplete for a financial tool: it does not mention that the transfer supports USD (despite wallet_currency in schema), lacks any return value expectation (no output schema), and omits potential failure modes. Given the tool's complexity, a bit more context would be beneficial.

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?

The schema already describes wallet_id, username, and amount (60% coverage). The description adds value by clarifying that the username triggers a wallet lookup, but it does not explain memo or wallet_currency. Given medium schema coverage, the description is adequate but not heavily compensatory.

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 clearly states the action: 'Send Bitcoin to a Blink user by their username.' It also distinguishes itself from sibling tools by emphasizing the intraledger transfer mechanism (free, instant), which differs from sending to a wallet ID or via onchain/invoice methods.

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 implies when to use this tool: when you have a Blink username to send to. It does not explicitly compare with alternatives like send_to_wallet or pay_invoice, but the username focus provides clear context. Lacks exclusionary guidance but is not misleading.

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