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

Annotations already declare readOnlyHint/idempotentHint/destructiveHint, but the description adds real context: it explicitly states it does not sign, broadcast, or authorize spending, discloses the Bearer-token auth requirement, and warns against re-paying after an uncertain result with a hash-reconciliation step. That is genuine added value beyond the structured fields.

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?

Four tight sentences, front-loaded with what the tool does, then constraints and safety guidance. No filler; each clause carries weight, though the telegraphic style borders on fragmented.

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 one-parameter tool with no output schema, the description covers the safety profile, auth needs, and a post-call reconciliation step (implying a returned hash). The only real gap is that it never explains the sole required parameter.

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 description coverage is 0% for the single request_id parameter, so the description carries the burden of explaining it. It says nothing about what request_id is, its format, or its idempotency role, despite 'exact-amount allowlisted' hinting that amount data matters.

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 ('Prepare') and resource ('unsigned exact-amount allowlisted token transfer'), so an agent knows exactly what is produced. However, it never distinguishes itself from siblings like prepare_donation, prepare_solana_payment, or prepare_escrow_action, so sibling disambiguation is left implicit.

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?

Provides real operational workflow guidance ('Requires wallet-session Bearer token', 'Obtain scoped payer authorization before signing', 'Never pay again after an uncertain result'). But it gives no condition for choosing this tool over the many other prepare_* siblings, so when-to-use-vs-alternatives is only implied.

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