Set plan block status

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

Annotations already declare this as a non-read-only, non-destructive, idempotent operation. The description adds behavioral nuance by explaining that recurring blocks track completion per-day, which is not captured by the annotations or schema. No contradiction is present.

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?

The description is a single sentence with around 18 words, front-loaded with the verb 'Mark'. It conveys the essential scope and recurring-block nuance without any 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?

The description provides the essential behavior, the per-date scope, and the recurring-block special case, which is sufficient for a simple status mutation tool. It does not specify the return value, but given the absence of an output schema and the simplicity of the operation, this is not a critical gap.

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?

The input schema has 100% coverage with descriptions for all three parameters, including an enum for status. The tool description adds no additional parameter semantics beyond the schema's existing descriptions, so the baseline of 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?

The description uses the specific verb 'Mark' with the resource 'day-planner block' and clarifies the scope as 'one specific local date'. It also distinguishes from the sibling 'update_daily_plan_block' by noting that recurring blocks track completion per-day, not globally.

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 description clearly implies the tool is for setting completion status on a specific date, and the note about recurring blocks helps users decide when this tool is appropriate. However, it does not explicitly name alternative tools or state when not to use it, so it falls short of a top score.

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