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

Annotations already declare destructiveHint=true, readOnlyHint=false and idempotentHint=true. The description adds real value beyond them by bounding the blast radius ('Saves the change to the user's LeakData action plan; it does not change anything on the breached site') and clarifying that done=false reopens, so the write is reversible within the plan. No error/permission behavior is described, which keeps it short of a 5.

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?

One dense paragraph, but nearly every clause carries a distinct rule (precondition, source of stepId, side-effect scope, the multi-step carve-out). Slightly heavy and led by usage rather than the action, though nothing is 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?

An output schema exists so return values need no explanation. Prerequisites, the fallback tool, the meaning of both parameters, the non-effect on the breached site, and the multi-step edge case are all covered — nothing an agent needs to call this correctly is missing.

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 coverage is 100%, so the baseline is 3, but the description goes further than the schema: it maps done=true/false to mark-vs-reopen semantics and constrains stepId's provenance to a leakdata.action_plan result, warning against guessing. That is genuine added meaning beyond the field descriptions.

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 (mark/unmark a step in leakdata.action_plan) and names the exact sibling artifact the stepId comes from. An agent can distinguish this from leakdata.action_plan or the lookup tools 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?

Explicit preconditions (only after the user confirms completion), explicit alternatives (call leakdata.action_plan first if no plan result exists in the conversation), and an explicit exclusion ('a request to mark all or several steps done is not confirmation… call this once per confirmed step'). 'Never guess a stepId' closes the remaining misuse path.

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