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

Annotations only declare non-read-only, open-world, non-idempotent, non-destructive; the description adds the costly, consequential details: account requirement, credit spend of 700–1,800 per drawing with a pointer to get_credit_balance, and a 1–5 minute asynchronous runtime before results are retrievable. This is exactly the behavior an agent needs before committing the user's credits.

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?

Front-loaded with the activation condition, then prerequisites, cost, latency and next step in that order. Every clause carries decision-relevant information; nothing is repeated from the title or annotations.

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 non-idempotent, credit-spending, multi-minute generation tool with a nested sketch object, the description covers trigger, prerequisite confirmation, cost, latency and the follow-up call. An output schema exists, so omitting a return-value breakdown is fine; the drawing_id hand-off is still noted.

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 100%, so the schema already explains brief, units, sketch and sketch_url. The description adds only mild context — that the sketch may be an attached photo/screenshot and is optional — and says nothing extra about the units enum or the brief's required content. Baseline 3 is appropriate.

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 resource ('draw or design a floor plan as a real CAD drawing') and enumerates the produced artifact (layered, dimensioned plan with walls, doors, windows, furniture, dimensions, room names/areas). This clearly separates it from get_cad_drawing (retrieve) and change_cad_drawing (modify) without opening any schema.

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?

Gives an explicit trigger ('when the user asks to draw... and wants it made now') plus a prerequisite ('confirm the brief with the user before starting') and the follow-up route ('then call get_cad_drawing with the returned drawing_id'). No explicit when-not or pointer to search_house_plans/get_house_plan for users who want an existing plan rather than a new drawing.

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