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

Annotations already declare read-only, open-world, idempotent and non-destructive behavior, so the safety profile is covered. The description adds genuinely new information by disclosing the cost model ('Flat 5 points per successful run'), which is not in the annotations and helps the agent budget calls. It stops short of describing error or rate-limit behavior.

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?

Two tight sentences: the identification and scope first, the cost note second. No filler, no repetition, and the resource is front-loaded.

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 enumerates the returned fields, and the annotations cover the safety profile; the key input form is clear. It is close to complete for a one-parameter read tool, lacking only guidance on failure or empty-result behavior.

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% for the single 'shop' parameter, and the description merely restates the same two accepted forms (shop_code or URL) that the schema documents with an example. Baseline 3 is appropriate since the schema carries the full parameter burden.

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 ('Get one Rakuten Ichiba shop storefront') and enumerates the returned fields (name, description, logo, cover, rating, review count). It is clearly distinguishable from run_rakuten_shops_items in substance, but it never names or contrasts a sibling tool 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?

Usage is only implied: the agent can infer this is the single-shop lookup keyed by shop_code, but there is no statement of when to use it versus run_rakuten_shops_items or run_rakuten_items_search, and no prerequisites or exclusions are given.

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