market_compare_product_offers

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

Annotations already carry the safety profile (readOnly, openWorld, idempotent, non-destructive), lowering the bar. The description goes beyond them with non-obvious interpretation semantics: 'Zero prices are unavailable; percentage is not a discount' prevents agents from misreporting free items or discount percentages, and it summarizes returned content (cheapest branches, price spread, promotional fields). These are exactly the behavioral details that prevent invocation errors.

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?

Four sentences, each with a distinct job: purpose, usage guidance, return-value summary, and data interpretation caveat. The core action is front-loaded and every sentence earns its place with zero filler.

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 a rich output schema and complete annotations, the description covers purpose, usage, return values, and pitfalls — enough for an agent to invoke correctly. The remaining gaps are the undocumented 'identity' parameter and indirect sibling differentiation, which are minor against the schema's coverage.

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 80%, so the schema already documents latitude, longitude, depots, and distance with useful constraints. The description adds no per-parameter meaning and leaves the undocumented 'identity' parameter unexplained. Baseline 3 is appropriate since the schema carries the heavy lifting.

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 opening sentence 'Fetch one product and compare returned branch prices' states a specific verb, resource, and scope in one line. This clearly distinguishes it from market_get_product (single fetch without comparison) and market_search_products (search without branch-price comparison).

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?

'Use when a detail lookup or refresh is needed' gives explicit invocation context, and 'existing search offers can already answer price questions' provides a concrete when-not condition that routes agents toward search siblings. It stops short of naming market_search_products or market_compare_basket explicitly, so the routing is clear but not fully exhaustive.

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