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

Annotations already declare readOnlyHint=true and destructiveHint=false, so safety is covered. The description adds two useful behavioral facts beyond annotations: restricted services require fresh server-verified access or the call refuses, and there are no writes or access grants. It does not disclose cost/rate-limit behavior of a forecast call or the freshness requirement for the verification context.

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, no filler, front-loaded with the core action. But the telegraphic style ('Read bounded native reach_forecast insight') sacrifices clarity for brevity, and the access sentence is cryptic.

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 forecast tool with a nested required body, 3 params, no output schema, and no pushed-down description of the domain, the definition is thin. It omits what the forecast returns and how to supply required inputs (location_id, products, budget), which siblings imply but the description never connects.

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 only 33%, with nested 'body' object containing location_id, duration_days, currency_code, and products (product_code, budget_micros) largely undocumented. The description adds nothing about these parameters, leaving budget_micros units, duration_days bounds, and product_code format to the schema alone. It does not compensate for the low coverage.

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 verb-resource pairing 'reach_forecast insight' identifies the operation, and 'bounded' hints at scope. However, it doesn't explain what a reach forecast actually returns (estimated reach/impressions for a budget) or distinguish it from sibling google_ads_reach_locations and google_ads_reach_products, which clearly supply the inputs this tool consumes.

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 explicit when-to-use guidance or named alternative. The sibling set contains google_ads_reach_locations and google_ads_reach_products that appear to feed this tool (location_id, products), yet the description never routes the agent to gather those first. 'Restricted services ... otherwise refuse' implies a permission gate but not a usage condition.

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