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

Annotations already cover readOnly/idempotent/non-destructive/closed-world, so the bar is lower. The description adds non-obvious behavior: results are filtered by connect-time selection, the payload carries default_account_id, and the flag widens scope to all reachable accounts. It does not mention pagination or empty-result behavior.

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 tight sentences, front-loaded with what is listed and what is returned, then the flag behavior. No filler or redundancy.

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 one-parameter list tool with an output schema, the description supplies exactly the missing pieces: result scoping and the meaning of default_account_id. Return-format details are rightly left to the output schema.

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% and the single parameter is a bare boolean, so the description carries the burden — and it does, explaining that all_accessible=true returns every account the credential can reach versus the default selected-accounts set. The default=false semantics are left 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?

States a specific verb (Lists) and resource (connected Meta ad accounts) and immediately scopes what is returned, which cleanly separates it from sibling listers like list_linkedin_ad_accounts or list_accounts. An agent can identify it without opening 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?

Explains the selection condition (only accounts chosen at connect time) and the alternative mode (all_accessible=true returns everything the credential can reach), which effectively tells the agent which invocation to pick. It does not explicitly name a sibling tool or state prerequisite connection steps, so it stops short of full routing guidance.

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