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

Annotations already cover readOnly/openWorld/destructive, so the description only needs to add context beyond safety. It does: the accepted handle prefixes, the outcome set (status/channel vs not_found_or_expired), and the anti-polling instruction. The return-value detail is somewhat redundant given an output schema exists, which keeps this from a 5.

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 the core verb and resource, then parameter formats, then the sibling redirect. Dense but every clause carries information; the accepted-format list is packed into one compact phrase rather than a list.

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?

With annotations, an output schema, and one required parameter, the description supplies the missing pieces: handle formats, result semantics, polling guidance, and the sibling alternative. Complete enough to invoke correctly; only the upstream link to connections_create_intent is left implicit.

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 0% for the single required parameter, so the description carries the burden — and it does, enumerating the three acceptable intent_id formats (ci_*, Meta connect_id, fbconn_live_*). It stops short of format syntax or validation rules, so it compensates well but not exhaustively.

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 ("Check one existing authorization handle") plus the point in the flow ("after the user finishes"). It also distinguishes itself from the closely related setup_check_channel_connect by routing setup connect_ids there, so an agent can separate it from siblings without reading the schema.

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?

Names an explicit alternative ("For setup connect_id use setup_check_channel_connect") and a behavioral caveat ("do not start automatic polling"), which is real routing guidance. The trigger condition is only loosely implied as "after the user finishes" — it never says the handle comes from connections_create_intent, so the when-to-use framing is clear but not fully closed.

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