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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false. The description adds that it displays fetched rows, but does not explain whether rendering produces a persistent artifact, what kind of report is generated, or any other behavioral trait beyond the safety profile already covered by annotations.

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 a single efficient sentence with the core action front-loaded. Its brevity is appropriate structurally, though it leans toward under-specification rather than violating conciseness.

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?

The tool has 7 parameters, nested row objects, an enum, and an output schema. The description does not explain required inputs like 'title' and 'rows', optional grouping via 'level', or series/currency/date-range usage, leaving significant gaps for a relatively complex rendering tool.

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% across 7 parameters, including required 'title' and 'rows' plus optional 'level', 'notes', 'series', 'currency', and 'date_range'. The description only loosely references 'rows' and 'report' but does not explain the role or format of any parameter, so it fails to compensate for the undocumented schema.

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 states a specific verb ('Show') and resource ('fetched performance rows as a report'), making the tool's purpose clear. It does not explicitly differentiate itself from related reporting or insights tools, but the word 'fetched' signals that it renders already-retrieved data rather than querying it.

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 guidance on when to use this tool versus alternatives such as insights_query_overview, insights_export_csv, render_ads_console, or render_ad_previews. The only clue is 'fetched', implying use after data retrieval, but this is not stated as a condition.

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