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

Annotations already flag this as a mutating, non-idempotent, open-world call, so the safety bar is lower; the description adds real context on prerequisites and quotes the specific Meta error (#27) that indicates the operation is unsupported. It does not mention what taking control does to the other app's session state (e.g. whether the previous owner is notified via handover).

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?

Front-loaded with purpose then prerequisites then fallback; four sentences, each doing work. The quoted error string is long but it is genuinely actionable for diagnosing the failure, so the density is justified rather than bloat.

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 2-param mutation with no output schema, the description covers prerequisites, failure mode, alternative, and a brief return statement ('Returns the chat'). Minor gap: no note that the call is non-idempotent, though annotations carry that.

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 100% — both chat_id (hashid or external_conversation_id) and the optional metadata note are documented there, including the handover-webhook destination. The description adds nothing about parameters beyond the schema, so baseline 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 and object ('Take a conversation back from whichever app holds it') plus the supported platforms (Facebook, Instagram via Facebook Login). An agent can tell this apart from the pass/release/request siblings because it names the request alternative for the unsupported case.

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 are given (Conversation Routing enabled, Postproxy allowed to take control), along with the exact failure mode and the fallback instruction 'use dm_chat_thread_control_request then'. That is a when-to-use / when-not-to-use / alternative triple in one paragraph.

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