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

Annotations supply only destructiveHint=true; the description adds the crucial nuance that the state change is reversible via a specific sibling, and reveals the underlying DELETE endpoint. It does not cover permissions or side effects on list search/matching counts, so it is strong but not exhaustive.

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 sentences, zero filler: purpose and effect first, reversibility second, endpoint reference last. Nothing is buried and nothing is repeated from the title beyond what adds value.

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 two-parameter mutation with no output schema and only a destructiveHint annotation, the description supplies the essential missing context (what changes, how to undo it). Minor gaps remain on required permissions and downstream effects, but nothing blocks correct invocation.

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?

With 100% schema description coverage on both parameters, the schema already documents list_id and item_id fully. The description adds no format, ID-source, or constraint detail beyond what the schema provides, so the baseline of 3 applies.

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 (archive) and resource (a list entry), plus the observable effect ('so it stops matching'), which distinguishes it from delete/update siblings. It also names the exact inverse tool, castle_unarchive_list_item, so the agent can place it precisely in the tool family.

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?

It gives real routing guidance by naming the counterpart tool that undoes the operation, making the archive/unarchive pair unambiguous. It stops short of an explicit when-not clause (e.g., why archive instead of delete or update), so it is clear context rather than full when/when-not coverage.

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