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

Beyond the annotations (readOnly=false, destructive=false), the description discloses two things the annotations cannot: the output is persisted to the Library, and the call consumes one generation of quota. It also reassures that nothing is sent or published, scoping the mutation's blast radius. It does not cover whether the generated text is returned inline.

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 short sentences, front-loaded with the capability and followed by the two facts that matter operationally (Library persistence, generation cost) and the reassurance about side effects. No filler or repetition of the title.

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 three-parameter generation tool with full schema coverage and explicit annotations, the definition covers cost, persistence, and safety adequately. The one gap is the return behavior: it says output is saved to the Library but not whether the copy itself is returned, which matters for an agent deciding whether to call list_saved_outputs afterward.

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%, so all three parameters (details, template, business_profile_id) are already documented in the schema, including the conditional multi-business requirement. The description adds no parameter-level meaning beyond that, so the baseline of 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?

The description names a specific verb and resource ("Creates Meta ad text and written creative concepts"), which clearly separates it from sibling copy-writing tools like write_email_copy or write_page_copy. It stops short of explicitly contrasting itself with those siblings, so it is clear but not fully differentiated.

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?

Usage is only implied through the phrase "Meta ad text" and the single-value enum 'meta-ad-copy'; there is no explicit statement of when to pick this over improve_existing_copy or the other copy tools. No prerequisites or exclusions are given.

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