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

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint, so the safety profile is covered; the description's 'Changes nothing in the ad account' mostly restates it. The only genuinely additive behavioral detail is that per-operation parameters must be fetched via get_tool_schema, which is useful but thin given the annotations carry the rest.

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?

The purpose is front-loaded in the first clause, which is good. The bulk of the text is a 28-item enum that duplicates the schema's operation enum verbatim, so a large share of the description is not adding information the agent doesn't already have.

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 multiplexer exposing 28 distinct read operations with no output schema and a 0%-documented nested params object, the description provides no per-operation semantics or return-shape hints. Pointing to get_tool_schema is a valid escape hatch, but on its own it leaves the agent unable to choose an operation without an extra round trip.

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 0%, so the description carries the full burden and largely fails it. It only points at another tool ('Parameters of an operation: get_tool_schema') instead of explaining the generic 'params' object, its nested shape, or what arguments each enum value expects.

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?

The description states a specific verb+resource class ('Meta Ads, read-only operations') and enumerates the 28 operations the tool dispatches, and the title plus 'read' framing distinguishes it from the sibling meta_ads_changes. However, the operation names are listed without any indication of what each one actually returns or does, so an agent still cannot tell operations apart from the description alone.

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?

'Changes nothing in the ad account' implicitly routes writes to meta_ads_changes, and 'Parameters of an operation: get_tool_schema' tells the agent how to obtain params before calling. There is no explicit when-to-use guidance for any individual operation, so the routing signal is implied rather than stated.

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