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

Annotations cover the safety profile (destructive, non-idempotent, closed-world), and the description goes well beyond them: it discloses the permission precheck, the subscription side effect, a background sync start, and the exact success condition ('Leads are only marked enabled once Meta has accepted the subscription'). This is meaningful behavioral context an agent would otherwise have to guess.

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-loads the purpose, then adds behavior and constraints; every clause carries information (permissions, subscription, sync, success condition, admin-only, feature gate). Slightly dense but no filler.

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 side-effecting mutation with no output schema, the description adequately covers prerequisites, side effects, and the completion condition. It does not describe what the caller observes after enabling (e.g., sync timing or return payload), leaving a minor gap.

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?

Only one parameter with 100% schema description coverage ('ID of the Facebook Page channel'), so the schema already carries the meaning. The description adds no additional format or sourcing detail beyond what the schema states, so the 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 ('Enable') and resource ('Lead Ads on a Page'), and its inverse sibling disable_facebook_page_leads makes the scope unambiguous without opening either schema. The description goes on to enumerate the concrete sub-operations (permission check, subscription, background sync).

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?

Clear prerequisites are given ('Administrators only', requires feature facebook_marketing) plus the operational context of which permissions must be present. It stops short of explicitly naming alternatives (e.g., disable_facebook_page_leads or sync_facebook_lead_forms) or stating when-not-to-use.

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