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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false, so the safety profile is covered. The description adds genuinely useful behavioral context beyond that: empty dates default to the last 30 days and customer_id is auto-detected, which tells the agent what happens when inputs are omitted.

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?

Three compact sentences, front-loaded with the purpose and then the input defaults. Nothing is redundant, though it is telegraphic and could be marginally clearer about the required account_id.

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 simple reporting tool with an output schema present (so returns need not be explained) and annotations covering safety, the description supplies the key input defaults. The remaining gap—the required account_id semantics and sibling differentiation—is minor but present.

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 usefully documents the expected YYYY-MM-DD format and defaults for start_date/end_date and the auto-detection behavior for customer_id, but says nothing about account_id, the one required parameter.

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 ('Microsoft Advertising campaign performance report') and enumerates the returned metrics (spend/impressions/clicks/CTR/conversions). It is clear on what the tool does, though it does not explicitly differentiate itself from similar siblings like microsoft_entity_performance_report or microsoft_search_terms_report.

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 explains default behavior (empty dates, auto-detected customer_id) but offers no when-to-use guidance and never names an alternative sibling report. An agent gets no routing help for choosing this over the other Microsoft/performance report tools.

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