Complete Goal

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

Annotations only say readOnlyHint=false, destructiveHint=false, which doesn't convey the side effect or idempotency. The description adds crucial context: it is idempotent, sets a flag, and returns goal_completed as True. It also clarifies the exact timing condition, going well beyond annotations.

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?

Each sentence earns its place: purpose, timing condition, prohibition, sibling distinction, idempotency note, and return value. The structure is front-loaded with the purpose and flows logically. No fluff.

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?

Given no parameters and no output schema, the description covers all essential information: what the tool does, when to call it, when not to, how it differs from a sibling, and its behavioral properties. This is fully complete for an agent to invoke correctly.

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?

With 0 parameters, the baseline is 4. The description explicitly states 'Takes no parameters' and mentions the return value, which is sufficient since there's nothing to explain about arguments. It adds no unnecessary parameter details.

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 starts with a specific verb+resource: 'Mark the current Sitting's Goal as completed', and immediately clarifies the condition ('once the story has actually resolved it'). It also distinguishes from sibling tool draw_goal_card by location in play (start vs later), satisfying the need for differentiation.

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?

Explicit when-to-use and when-not-to-use: 'Call at most once per Sitting, only after an Omen's grounding has landed... never call this preemptively'. It also names an alternative (draw_goal_card) and explains the boundary (deals vs marks finished). This is textbook usage guidance.

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