get_account_performance_summary

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 nothing behavioral beyond that: it does not say which metrics are aggregated, what timezone or currency applies, whether zero-spend days are included, or how large a date span is tolerated.

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 lines plus a short Args block; the purpose sentence is front-loaded and there is no filler prose. The Args formatting is conventional boilerplate rather than added value, but nothing is wasteful or padded.

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?

With no output schema, the description should indicate what a 'performance summary' contains, since 'performance' could mean cost, clicks, impressions, conversions, or all of them. For a read-only reporting tool with only two parameters that is a meaningful omission, though the input surface itself is adequately documented.

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 must carry the parameter burden, and it does partially: it identifies customer_id as a Google Ads customer ID and gives the accepted date_range syntax ('YYYY-MM-DD,YYYY-MM-DD' plus a predefined option). However, it never enumerates the valid predefined tokens (the schema only hints LAST_30_DAYS as a default), leaving the most error-prone part of the parameter underspecified.

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 gives a specific verb and resource ('Get account-level daily performance summary') with scope qualifiers (account-level, daily) that separate it from the campaign-, ad-group-, and keyword-level performance siblings. It stops short of naming an alternative explicitly, but the resource granularity is clear enough to choose between tools.

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 or when-not-to-use guidance, and no routing to alternatives such as get_campaign_performance when a breakdown is needed. The agent must infer selection criteria purely from the word 'account-level'.

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