get_campaign_performance

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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds useful operational detail — accepted date_range formats, the LAST_30_DAYS default, and the default row limit of 50 — but says nothing about pagination behavior, zero-row campaigns, or whether cost figures are in micros.

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 one-line purpose is front-loaded, followed by a compact Args block that maps one-to-one onto the five parameters. No filler, though the Args-list format is slightly verbose relative to the short 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 read-only analytics tool with no output schema, the description should hint at which metrics are returned; 'campaign performance metrics' is unspecified. Parameters are otherwise fully documented, and annotations handle safety, so the definition is callable but not fully self-explanatory.

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 and does it well: it enumerates predefined date ranges plus the custom 'YYYY-MM-DD,YYYY-MM-DD' format, lists valid status values, and notes campaign_id is optional. Gaps remain on customer_id format expectations and limit semantics (max vs. page size).

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?

Names a specific verb and resource: 'Get campaign performance metrics over a date range.' Combined with the tool name, an agent can tell it apart from siblings like get_ad_group_performance or get_account_performance_summary by level of aggregation. It does not, however, explicitly state the distinction from those siblings.

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 by the parameter list: filtering by campaign_id or status_filter suggests narrowing a campaign-level report. There is no explicit statement of when to prefer this over get_account_performance_summary, get_ad_group_performance, or execute_gaql, and no prerequisites or exclusions.

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