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

Annotations already declare readOnlyHint=false, destructiveHint=false and openWorldHint=true, so the mutation and open-world profile is covered. The description adds only that criteria must be 'Facebook-supported', hinting at validation of unsupported values, but says nothing about whether creation is idempotent, how duplicate names are handled, or what is returned.

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 with the core action front-loaded and no filler. Nothing is wasted, though the second sentence largely restates the categories already visible in the schema.

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 creation tool with no output schema, the definition omits anything about what the call returns (e.g., an audience identifier) or that a created audience still needs to be attached to a campaign. With 100% schema coverage and annotations present, the gaps are moderate rather than critical.

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 every parameter, including the enum-constrained countries and industries lists and the estimate_only preview flag, is already documented. The description's mapping of criteria categories to parameter concepts is mildly helpful but adds no syntax or format detail beyond 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?

The description uses a specific verb+resource ('Create a Facebook native criteria audience') and enumerates the targeting dimensions it supports (industries, location, job titles, interests, age range). The 'Facebook' qualifier implicitly separates it from the LinkedIn counterpart, though it never names that sibling explicitly.

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?

There is no when-to-use guidance and no exclusions or alternatives given, despite many sibling audience-creation tools (create_linkedin_native_criteria_audience, create_firmographic_audience, create_audience_from_segment, create_technographic_audience). An agent must infer from the name alone which creator fits a given request.

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