explain_traffic_change

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

Annotations already provide readOnlyHint, destructiveHint, idempotentHint, and openWorldHint. The description adds behavioral context by detailing the returned data: overview, deltas, top 5 pages/referrers, anomaly-day callouts (z-score >= 2), and daily series. It also explains how to interpret the output, enhancing transparency beyond 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 front-loaded with purpose, then structures the output list and usage advice. Every sentence adds value, though it could be slightly more concise. It is well-organized for an AI agent to parse.

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 the tool's complexity (multiple output components) and the presence of an output schema, the description is complete: it covers purpose, behavioral details, and usage guidance. It does not need to explain return values since the output schema exists.

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%, with both parameters well-described (site_id as UUID from list_sites, date_range as enum with defaults). The description adds no new parameter information beyond noting the tool works 'on a specific site' and 'vs prior period.' With high schema coverage, a baseline of 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 starts with 'ANSWER FIRST for any 'why did traffic [spike/drop/change]' question on a specific site,' clearly stating the verb (explain) and resource (traffic change on a specific site). It distinguishes from sibling tools like get_site_traffic and detect_anomalies by positioning itself as the go-to explanatory tool.

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 explicitly says 'ANSWER FIRST' for specific questions, guiding when to use it. It also provides usage instructions like using gainers/losers lists to attribute changes and not pasting raw arrays. While it doesn't explicitly state when not to use it, the context signals and sibling tools imply differentiation.

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