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

Annotations already declare destructiveHint=true and readOnlyHint=false, and the description adds real value beyond them: it explains that the goal_end names every purchase that served the goal and that no further purchases happen, plus the auth requirement ('Needs your key'). It does not address reversibility or what happens if the goal is closed twice (idempotentHint=false), which keeps it below a 5.

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 ordered as purpose, effect, then inputs/auth, so the important part is front-loaded. Slight jargon ('goal_end', 'because') assumes prior context, but there is no 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 destructive, no-output-schema mutation the description covers the trigger, the effect on future purchases, the required inputs and the key requirement. Missing only the post-close state (whether the goal can be reopened, what the signed goal_end returns).

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% and the schema already documents goal, goal_sha256 (with the 'instead of the goal text' alternative) and the reached/abandoned outcomes. The description restates the either/or ('same goal text you gave in because, or its goal_sha256') and adds the useful tie-back to the because call, but that constraint is largely already in the schema.

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 and effect: it signs a goal_end record naming every purchase that served the goal, and stops further purchases for that goal. This clearly distinguishes it from sibling purchasing tools like buy or set_budget, since the agent can tell this is the termination step, not a purchase step.

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 opening clause gives clear trigger conditions: the principal's task is done (reached) or given up (abandoned). No explicit exclusions or named alternatives are offered, but the outcome enum plus the 'nothing more is bought' note makes the appropriate moment unambiguous.

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