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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context about the split logic and brand-word configuration, but it does not disclose details such as the comparison period or data lag; those appear only in the schema. This is acceptable given the annotation coverage, though not especially rich.

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 concise sentences with no filler. The main purpose is front-loaded and the setup instruction ('Set your brand words in Settings') is included without redundancy. Every sentence earns its place.

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 report tool with full schema coverage and safety annotations, the description provides the core purpose and the essential non-obvious setup step. The absence of an output schema means the description could do slightly more to describe return values, but the description's split definition and the schema's comparison details together give an agent sufficient context to invoke it correctly.

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 coverage is 100%, so the schema fully documents all three parameters (days, site, terms) with meaningful descriptions. The tool description adds context around brand words and their relation to Settings, but this is marginal beyond what the schema already states. Baseline 3 is appropriate.

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 clearly identifies the tool's function: splitting searches into branded and non-branded segments, with a specific verb ('splits searches') and resource ('searches'). It conveys the purpose effectively but does not explicitly differentiate from sibling tools like search_performance or measure_change.

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 description implies when to use the tool ('so growth is not hidden behind your own brand') and mentions configuration ('Set your brand words in Settings'), but it does not explicitly state when to use this instead of an alternative sibling tool or give exclusion criteria. Usage context is present but under-specified.

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