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

Annotations already declare readOnlyHint=true, openWorldHint=false, destructiveHint=false, so the agent knows this is a safe, non-destructive, closed-world operation. The description adds the routing behavior and the instruction to preserve qualifiers, but says nothing about latency, failure modes, or the shape of what the router returns.

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 imperative 'Start here for any shopping request,' and each subsequent sentence adds a distinct instruction (qualifier preservation, when to prefer, alternatives). Slightly verbose but without 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?

For a router with no output schema and a fully documented input schema, the description covers the essential decisions: entry-point role, routing targets, and sibling relationships. It could say more about what the router returns or when it escalates, but the calling guidance is 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 coverage is 100%, so the schema already documents all five parameters, including the note that intent/brand/budget_max/product_refs are 'secondary hints.' The description largely restates the request-parameter guidance ('Pass the shopper's COMPLETE request ... preserving every qualifier') that the schema already contains, so baseline 3 applies.

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 role clearly: an entry-point router that 'will understand it and route to the right capability (personalized recommendation, catalog search, product lookup, or comparison).' It distinguishes itself from siblings by explicitly naming the granular tools (search_products, get_product, compare_products, create_checkout) it sits above.

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?

Gives an explicit selection rule — 'Prefer this tool whenever the request is conversational or carries any nuance' — and names the alternatives plus the condition for descending to them ('granular tools ... remain available as precise follow-ups'). Both when-to-use and when-to-use-alternatives are covered.

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