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

Annotations already declare readOnly=false, idempotent=true, and destructive=false, so the safety profile is covered. The description adds genuine cross-entity behavior that annotations cannot convey: done=true also completes the linked path step, and count>0 ticks while 0 unticks. It stops short of describing permission requirements or full side-effect scope.

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 sentence structure is front-loaded, starting with the core verb+resource before drilling into per-parameter semantics. For a 12-parameter tool, the length is defensible, though the routine/'bad-day minimum' clause is dense and slightly redundant with the schema enum.

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 annotations covering safety and no output schema to explain, the remaining burden is on documenting the 12 parameters and the linked-entity model. The description handles the done/count/level semantics but omits how the linking parameters (stepId, leverId, projectId, date) relate to the plan item, leaving an agent to guess at a non-trivial mutation surface.

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 only 25%, so the description must carry more weight. It explains done, count ('how many units this tick did'), and level ('counts for the day, reported apart from full') well, but leaves itemId, stepId, leverId, projectId, date, and isMainStep undocumented in both schema and prose. It clarifies the highest-value parameters but does not fully compensate for the coverage gap.

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 opens with a specific verb ('Change') and resource ('one plan item') and enumerates the editable aspects (done status, title, estimate, area, links, main step), so the agent knows exactly what surface this tool covers. It does not explicitly name or distinguish itself from siblings like edit_step or edit_milestone, which is the only thing keeping it from a 5.

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?

Usage is implied through conditional semantics ('For a weekly routine, count says...', 'For a routine, level minimum...'), which tells the agent when certain parameters apply. However, there is no explicit guidance on when to use edit_plan_item versus set_plan, edit_step, or edit_milestone, leaving alternative routing to inference.

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