placements

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

Despite no annotations, description fully discloses MODE (mixed), AUTH (OAuth 2.0), CREDITS (reads=0, writes=0.5), and output fields. For each action, it explains behavior, e.g., 'archive_placement' is 'Destructive write — removes from targeting options.'

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?

Description is well-structured with sections (purpose, MODE/AUTH/CREDITS/OUTPUT, WHEN TO USE). Every sentence adds value; no 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 2-parameter tool with enum actions, description covers all essential aspects: purpose, behavioral traits, when to use, output structure, and differentiation from siblings. No gaps.

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% with detailed enum explanations for action. Description adds no additional parameter semantics beyond what's in the schema, so baseline 3 is appropriate.

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?

Description clearly states 'Manage GAM placements — named groups of ad units for targeting.' It distinguishes from sibling tools by noting 'Use inventory for individual ad unit management' and references targeting tool for line item targeting.

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?

Explicit 'WHEN TO USE' section explains when to use placements (creating named groupings for targeting in line items) and when not (use inventory for individual ad unit management). Provides clear context.

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