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

Adds real behavior beyond the idempotentHint/destructiveHint annotations: the copy scope is limited to selected items, and 'no other chat history or reply/private references are copied'. The 'expected_* unchanged from preview' instruction also discloses an optimistic-concurrency guard the annotations do not reveal, though failure behavior on mismatch is unstated.

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 tight sentences: operation first, precondition second, parameter provenance and scope boundary last. No filler and every sentence adds a distinct constraint.

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 5-param mutation with no output schema, it covers purpose, precondition, the optimistic-concurrency contract, and scope exclusions. Remaining gaps are the item-count limit and what happens when expected_* no longer matches the live state.

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 0%, so the description carries the burden, and it clarifies the provenance of expected_members and expected_items (must be passed unchanged from preview). However chat_id, project_id, and item_ids get only loose coverage, and the 20-item maxItems cap is never mentioned.

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 ('Copy ... direct-chat messages into the selected shared project') with clear narrowing to 'only the selected' items. This cleanly separates it from preview_direct_chat_share and the many other share-related siblings.

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?

Gives an explicit precondition: it runs 'after the user reviewed the preview and its recipient scope', which effectively routes the agent through preview_direct_chat_share first. It does not name that sibling outright or state what to do when the preview was not run, so it falls just short of the top tier.

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