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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds useful behavioral context by listing the exact fields returned (name, campaignId, state, budget, tactic, costType, bidOptimization) and stating that performance is not returned. It does not disclose pagination or result limits, which keeps it from a 5.

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 the resource and its live/existing scope, then quickly enumerates return fields and exclusions. Each sentence earns its place by clarifying scope, preventing misuse for creation or performance queries, and naming the alternative. There is no redundant or filler content.

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?

With no output schema, the description usefully explains the main return fields and states that performance data is absent. However, it gives no guidance on how to use the filter parameters or what results look like beyond the field list. For a list tool with four parameters and low schema coverage, this is adequate but incomplete.

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 only 25%, and the description does not explain the input parameters account_id, profile_id, state_filter, or campaign_id_filter. It mentions state values (enabled|paused|archived) as returned fields, but does not connect them to filtering behavior. With four parameters and low schema coverage, the description fails to compensate for missing parameter semantics.

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 states a specific verb and resource: listing LIVE existing Sponsored Display (SD) campaigns. It enumerates returned fields and distinguishes this tool from Sponsored Products/Sponsored Brands siblings by explicitly scoping to SD. It also clarifies that Vendooly does not create SD campaigns, preventing confusion with creation tools.

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 gives explicit when-not guidance: Vendooly does not create SD campaigns, and this tool does not return performance data. It names the correct alternative for performance analysis, instructing the agent to use execute_sql on fact_campaign_daily with ad_product='SD'. This clearly routes the agent away from using this list tool for metrics.

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