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

Annotations already declare this a non-read-only, idempotent, destructive, open-world mutation, so the safety profile is covered. The description's contribution is that the operation is bidirectional and reversible via done=false, which usefully softens the destructive framing. It says nothing about auth requirements (participant token) or what happens when item_id does not resolve to a valid text match.

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?

Two sentences, no filler, and the state semantics are front-loaded before the usage hint. Every clause carries information an agent would otherwise have to guess.

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 five-required-parameter mutation whose plan/item_id/token semantics are spelled out in the schema, the description plus schema is enough to invoke correctly, and no output schema exists to need explaining. A brief note on what a failed item lookup does (the description hints the exact item text works via schema only) and on return behavior would close the remaining 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?

At 80% schema coverage the baseline is 3, and the description earns an extra point by giving semantics to the one parameter the schema leaves bare: done (type boolean, no description) is explained as done=true for finished and done=false for reopening. The other four parameters are fully documented in the schema itself.

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 ("Marks a checklist item done") and defines both directions of the toggle, which distinguishes it from the read-oriented get_checklist. It never names a sibling tool explicitly, so an agent must infer the boundary with add_checklist_item and get_checklist on its own.

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?

"Use when the user says a task is finished or needs reopening" gives a concrete trigger condition tied to user intent, which is exactly the signal an agent needs. There is no exclusion guidance (e.g. use get_checklist first to find the item_id), so it stops short of a full when/when-not statement.

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