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

With no annotations, the description carries the full disclosure burden, and it does deliver one genuinely non-obvious trait: '1 point per returned record' tells the agent this call consumes credits proportional to result volume, and 'live' signals real-time (non-cached) data. It omits rate limits, auth requirements, and paging 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, zero filler. The primary capability is front-loaded and the credit-cost caveat follows immediately; nothing is repeated or padded.

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 an 8-parameter search tool with full schema coverage and no output schema, the description covers what the tool does and its cost profile. The main remaining gap is the shape of the returned records (fields, paging semantics given start_page/max_items), which the agent must guess since no output schema exists.

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% with per-parameter descriptions and enum value mappings, so the schema already carries the semantics. The description's filter list (sort, condition, price range, genre) merely restates what the schema documents, adding no syntax or format detail — the 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 verb (Search) plus resource (live Rakuten Ichiba items) and enumerates the filter dimensions (sort, condition, price range, genre), which maps cleanly onto the schema. It does not explicitly distinguish itself from run_rakuten_items or run_rakuten_shops_items, though the 'by keyword' scope implies a search endpoint rather than a detail lookup.

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 by the search framing — an agent can infer it should be used when it needs keyword-based item discovery on Rakuten, but there is no explicit when-to-use statement, no prerequisites, and no routing to the sibling tools (e.g. run_rakuten_items for a known item ID).

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