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

Annotations already establish read-only, idempotent, non-open-world behavior, and the description adds genuine context beyond them: it is free/public tier, prices are per 1,000 tokens with modality-specific units, the May 2026=100 base, coverage/basket-change flagging, and that PRO-level vendor data requires a key. Return-format detail is thorough but pagination/size limits are not mentioned.

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-loaded with the one-line purpose, then families, then output contents, then examples - a logical order. It is somewhat long but nearly every sentence carries information an agent needs; no filler sentences.

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 carries the full burden and discharges it: it explains the benchmark level, spot price (median/p25/p75), the change dimensions, and coverage counts with basket flags. An agent knows what it will receive before calling.

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%, so the baseline is 3, and the description adds meaning through worked examples showing accepted code forms ('TXT', 'NCL', 'AIPI TXT GLB') and the category values that drive index_category. It clarifies the free-vs-PRO distinction of _atom_api_key beyond the schema text.

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 and resource ('Attic Standard price indexes for AI inference') plus the exact scope ('every published index at the week the site shows'). The six families enumerated make it clearly distinct from siblings like compare_prices or get_kpis, though no sibling is named explicitly.

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 three examples map real user questions to specific parameters ('Where is text inference priced this week?' -> index_code="TXT"), which gives clear context for when to reach for this tool versus the category-wide alternatives. No explicit when-not-to-use or named-alternative guidance is provided.

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