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

Annotations already declare readOnlyHint=true and destructiveHint=false. The description adds valuable paging behavior: it explains totalElements, totalPages, and instructs to paginate or increase size before compiling a list, warning not to report rows as unavailable. This is additional operational context beyond the annotations, so it scores well.

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 well-structured: a purpose sentence, a USE FOR list, a REQUIRED note, and a PAGING paragraph. It is front-loaded with purpose and each section is relevant. It is not overly verbose, though the PAGING section is a bit detailed. Overall, it is concise and organized.

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?

Given there is no output schema, the description provides essential operational details: date range requirement, pagination mechanics, and the fact it covers active experiments. It does not mention the optional keywordOrExperimentName filter or sorting, but those are in the schema. The description is complete enough for an agent to call the tool correctly, though it could briefly mention the return shape.

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%, so the baseline is 3. The description mentions date range format as YYYY-MM-DD, which slightly conflicts with the schema's ISO 8601 format with timestamps. It does not add substantial meaning for other parameters beyond what the schema already explains. It clarifies required parameters and paging, but this is marginal. Hence a 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 states the tool provides keyword performance data from active experiments with date range filtering. It lists specific use cases (Google Ads / Microsoft Ads keyword metrics, ROI, conversions) which distinguishes it from simple keyword listing tools. However, it does not explicitly name a sibling alternative, so it's clear but not maximally differentiated.

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 'USE FOR' section explicitly lists when to use this tool, covering keyword performance across experiments and specific metrics. It provides clear context but does not state when not to use it or mention alternative tools like list_keywords or experiment_performance_stats. Thus it has clear context but no exclusions, matching score 4.

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