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

Annotations already declare readOnly/idempotent/non-destructive, and the description adds result-shaping behavior beyond them: sorted by spend descending, default date window when dates are empty, and READ-ONLY confirmation. It does not cover pagination/limit behavior, but the extra context is real value.

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?

Front-loads the resource and its purpose, then the actionable insight, then parameter specifics. Dense but every sentence carries information; only the trailing READ-ONLY is redundant with annotations.

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?

Output schema is present so return values need no explanation, and annotations cover the safety profile. However, with 0% schema coverage and 7 parameters, several inputs and the limit/pagination behavior remain undocumented, leaving gaps for an agent configuring the call.

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%, so the description must carry the load. It fully explains min_waste semantics and date format (YYYY-MM-DD, empty = last `days`), but leaves days, limit, account_id, and customer_id undocumented for a 7-param tool.

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?

States a specific verb+resource — 'SEARCH TERMS report for Microsoft Advertising (Bing)' — and enumerates the contents (actual queries typed, matched keyword, match type). An agent can distinguish it from microsoft_performance_report and the generic search_terms_report immediately.

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?

Gives clear context for use: it frames the report as finding wasted spend and routes the agent to add_microsoft_negative_keywords as the follow-up action. It stops short of explicit when-not-to-use guidance or naming the expected input scope, but the intent is unambiguous.

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