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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds genuinely useful behavior context beyond that: the required X-Mako-Key header and the human-in-the-portal constraint for connecting Facebook. It stops short of describing what happens when no account is connected, but the added operational detail is above the annotation baseline.

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?

Three sentences, each earning its place: purpose first, then call ordering/why, then the prerequisite and auth requirement. No filler and the most important information is front-loaded.

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 read-only lookup with no output schema, the description covers purpose, ordering relative to build_paused_campaign, the human prerequisite, and auth. Minor gaps remain (e.g., behavior when no Meta account is connected), but nothing needed to invoke it correctly is missing.

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% and the single parameter is already documented as 'From list_clients.' The description adds no further meaning about client_account_id, so the baseline of 3 applies when the schema does the heavy lifting.

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 ('Show') and resource ('the client's connected Facebook ad account and the conversions available to optimize toward'), which is concrete enough to distinguish it from siblings like list_clients or list_creatives. An agent knows exactly what it retrieves 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?

Explicitly names when to call it ('before build_paused_campaign on a leads or sales campaign') and why ('those need a conversion to aim at'). It also states the out-of-band prerequisite that connecting Facebook has to be done by a person in the portal, which routes the agent away from trying to do it programmatically.

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