Drill down a Metrica report

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

Annotations already convey readOnlyHint and openWorldHint. The description adds useful behavioral details: each row has an 'expandable' flag, parentId carries the key path, and the tool returns only one level. The statement 'Requires dimensions' is ambiguous and conflicts with the schema's required field (metrics only), which slightly undermines transparency but does not contradict 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 three short sentences with the purpose front-loaded. It is concise, but 'Read-only' repeats the annotation and 'Requires dimensions' is marginally misleading, so it does not earn a 5.

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 tool with 15 parameters and no output schema, the description covers the essential navigation logic (parentId path, expandable flags, one-level scope). The response format is partially documented in the fullResponse parameter, so the description plus schema provide adequate context for invocation.

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 100%, and each parameter has a detailed description. The description adds minimal semantic value beyond echoing parentId behavior; 'Requires dimensions' is not even schema-accurate. Baseline 3 applies because the schema does the heavy lifting.

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 uses a specific verb ('Return') and resource ('one level of a hierarchical report'), and includes the endpoint path. This clearly differentiates it from sibling report tools like run_report or run_timeseries, which presumably return flat or non-hierarchical data.

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 context is clear: this is for hierarchical tree reports, and the description explicitly explains how to expand deeper using parentId. It also states a prerequisite ('Requires dimensions'). However, it does not explicitly name alternative tools or provide exclusion criteria, stopping short of a 5.

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