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

Beyond the annotations (write, non-idempotent), the description discloses what is preserved (planned, locked, or answered dinners stay put), that execution is asynchronous and queued, how to check progress (get_planning_status with the jobId), and that the run consumes the household's monthly credits. Those are exactly the side-effect and cost details an agent cannot get from 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?

Three short clauses, each front-loaded with the highest-value information: what gets filled, what is left untouched, then the async follow-up and credit cost. No redundant restatement of the name or title.

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, the description compensates by explaining the queued job model and the exact sibling to poll for status. Combined with the preservation guarantees and credit cost, an agent knows how to invoke it and what to do next without further lookups.

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?

There is a single parameter with 100% schema description coverage, so the schema already explains that any date in the week resolves to that week's plan. The description adds no format, timezone, or boundary details beyond that, which is acceptable at this coverage level.

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+resource (fill the open days of a week) and immediately scopes it to weeks that already have a plan, which distinguishes it from plan_week. The preservation rule and the routing to get_planning_status make the tool's identity unambiguous among siblings.

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 precondition 'a week that already has a plan' implicitly tells the agent to use plan_week for fresh weeks, and it names get_planning_status as the follow-up for the returned jobId. It does not explicitly say 'use plan_week instead if no plan exists', so the routing is inferred rather than spelled out.

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