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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so the safety profile is covered. The description adds only that results come 'cursor by cursor', which usefully signals pagination but says nothing about page sizing, ordering, or what a returned friend record contains.

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?

Two short sentences with no filler, and the core purpose is front-loaded before the availability caveat. It could carry one more clause of parameter guidance without becoming bloated.

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 zero-required-parameter read-only list tool with strong annotations and a well-annotated schema, this is close to sufficient. The remaining gap is minor: no indication of return shape or default page size, which matters only mildly since no output schema exists.

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 67% and the two most semantically tricky parameters — cursor (opaque next_cursor, no offset pagination) and account_id (unipile_account_id, not a person ID) — are fully documented in the schema. The description adds nothing beyond the schema's cursor framing, and `limit` is undocumented in both places, so baseline 3 is right.

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 ('List the account owner's friends') and scopes it to the account owner. It doesn't explicitly differentiate from near siblings like facebook_list_contacts, facebook_list_followers, or facebook_list_following, so an agent must infer that 'friends' means accepted mutual connections rather than followers or address-book contacts.

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?

'Other users' friend lists are unavailable' gives a useful when-not boundary. However, no positive context or named alternative is offered — the description never says to use facebook_list_friend_requests for pending requests or facebook_list_following for follows, so routing among the Facebook list tools is left to the agent.

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