google_ads_change_status

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

Annotations already provide readOnlyHint=true and openWorldHint=true, covering safety and world-openness. The description adds useful behavioral context beyond that: the tool is 'lightweight,' returns per-resource last-modified timestamps, and is limited to a 14-day window. These operational characteristics are not visible in the annotations and help an agent set expectations.

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 description is tightly written: a one-sentence summary, a clarifying comparison to change_event, and a short parameter list. Every line contributes value, and the structure front-loads the core purpose before diving into details.

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 tool with an output schema, the description covers everything needed to call it correctly: purpose, key behavioral traits, the 14-day limitation, and all four parameters with constraints. The sibling contrast addresses the main alternative. No significant gaps remain.

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 of parameter documentation, and it succeeds. Each parameter gets a concise semantic: customer_id is a 10-digit identifier, days_back has a 1–14 range, resource_types is an optional enum filter, and limit caps row count. This meaningfully compensates for the bare schema and enables correct argument construction.

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 clearly states the tool's function with a specific verb and resource: 'Lightweight change tracker: last-modified-at timestamps for resources.' It explicitly differentiates itself from change_event by describing itself as a per-resource 'last modified' view rather than a change-diff log, making it immediately distinguishable from its closest sibling.

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?

The description names the sibling tool change_event and draws a direct contrast: 'Unlike change_event, this is a per-resource last modified view rather than a change-diff log.' This strongly implies when to use this tool versus the alternative, and the 'covers up to 14 days' note sets clear scope boundaries. It stops short of explicitly stating 'use change_event for change-diff logs,' but the implication is clear enough.

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