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

Annotations already declare non-destructive, idempotent, open-world behavior, so the description only needs to add context — and it does, by bounding the blast radius ("scope is this thread: it does not stop the agent elsewhere... or change the lead itself") and by clarifying the tool cannot send a reply. It stops short of stating whether the change is trivially reversible for the non-archived flags, which would have completed the picture.

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 capability statement is front-loaded, followed by the highest-value scenario, then the boundary conditions. Every sentence carries routing or scoping information; there is no restatement of the title or the schema beyond what adds meaning.

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-parameter mutation with no output schema, the description plus annotations cover safety, scope, and alternatives well. The only omission is any indication of what the call returns or how partial updates behave (whether omitted fields are left untouched), which matters for an idempotent partial-update tool.

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 schema baseline is a 3; the description earns above baseline by explaining the operational consequence of `assistant: false` ("stops the bot replying so a person can take over"), which is meaning the schema's one-line field note does not convey. The other parameters (seen, isArchived, pauseBotOnManualMessage) are left entirely to the schema.

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 opening sentence names three concrete operations (archive, mark read, hand off between AI and human) on a clearly identified resource, a conversation thread. It is immediately distinguishable from siblings like conversation_mark_all_read or message_send, which the description also implicitly rules out.

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 when-to-use guidance: "the one call to make when an agent is answering badly and a human needs the thread," tied to the concrete `assistant: false` parameter. It also gives explicit when-not/where-else guidance by naming agent_upsert with isActive: false, campaign_update, and lead_update as the correct tools for the adjacent concerns.

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