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

Annotations already declare readOnlyHint=true, openWorldHint=true, destructiveHint=false, but the description adds meaningful context beyond them: the request is 'short-lived' and explicitly does not sign/create/pay/settle. For a prepare-step tool this negative-scope disclosure is genuinely useful for understanding the security boundary.

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?

Two tight sentences: the action is front-loaded, then the negative scope. No filler, and every clause carries information.

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 and only two parameters, the description covers purpose, scope limits, and the plan/amount semantics adequately. It leaves minor gaps around the exact returned artifact and any signing prerequisites, but nothing critical for a read-only prepare tool.

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%, so the description must carry the load, and it does: it maps the two plan modes (one-time donation versus fixed 2,100-sat 30-day membership) and states the donation range of 21 to 1,000,000 sats, matching the donation_sats min/max. It never names the 'plan' or 'donation_sats' fields, but the option semantics are substantially conveyed.

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 (signed-authorization request) and disambiguates from the create/sign/pay/settle toolchain by negation, which helps separate it from the sibling create_grynvault_supporter_invoice. However, 'signed-authorization request' is somewhat jargon-heavy and the sibling is not named explicitly.

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 phrase 'Does not sign, create, pay, or settle an invoice' implies this is the preparatory step before signing/creation, giving implied usage context. But it never states explicitly when to choose this over create_grynvault_supporter_invoice or what precedes/follows it, leaving routing to inference.

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