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

Annotations already declare readOnlyHint=true and idempotentHint=true, so the description adds valuable behavioral context beyond these: it 'returns the cheapest verified plans that actually answer phone calls, sorted by monthly price, excluding zero-minute teaser plans and add-ons', and notes that prices are human-verified with dates. This helps the agent set expectations about filtering and quality without being unnecessarily verbose.

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 primary purpose and uses three concise sentences. The list of example queries is slightly long but each item is specific and aids the agent in recognizing matching user intents. No fluff; every sentence contributes useful guidance.

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 no output schema, the description provides a clear sense of return behavior: cheapest verified plans sorted by monthly price, excluding teaser plans. It also covers typical use cases and quality filters. It does not detail the exact fields in the response, but for a comparison-list tool with 3 optional params, it is reasonably complete.

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% (all 3 parameters have descriptions), so the baseline is 3. The description reinforces that budgeting and type are core filter dimensions but does not add extra detail about parameter syntax or value interpretation. It adequately aligns with the schema, but adds no additional semantic value beyond what's already present.

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 a specific verb 'Compare' with resource 'answering services and AI receptionists' and specifies dimensions (budget, type). It differentiates from siblings by focusing on comparing costs and plans, while 'get_answering_service_pricing' likely retrieves raw pricing and 'recommend_answering_service_for_industry' is industry-specific. The use-case list further clarifies the tool's unique intent.

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 provides numerous 'when to use' triggers: questions about cost, cheapest service, AI receptionist under $100, comparison with in-house staff, etc. This gives clear context but does not explicitly mention when *not* to use the tool or name alternative sibling tools, so it does not earn a 5.

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