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

With no annotations, the description carries the full behavioral burden and does well: it discloses 'Read-only', 'No platform quota consumed', and what each item carries (detail_url to show the user, score+breakdown, buy guidance). It omits pagination/limit behavior and result-count semantics, but the safety and cost-profile disclosure is strong.

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 core purpose and quota benefit, then returning-item contents, then the sibling-routing decision. Dense but every sentence adds information; only mild loss from packing several facts into parentheticals.

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 7-param read-only search with no output schema and no annotations, the description covers the safety profile, cost, return-item structure, and tool selection. The remaining gap is per-parameter meaning for the filtering/pagination params that neither the schema nor the description explains.

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 0%, so the description should compensate. It explains the sort parameter thoroughly (default relevance with 3-factor explainable score and shop tiers, plus sales|price|latest), but says nothing about platform, price_min, price_max, page, or page_size, leaving five of seven parameters undocumented.

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 ('Search the LOCAL shelf') and immediately scopes it with parenthetical detail about the underlying curated taobao/jd/pdd items. It also distinguishes itself from the platform-search siblings by contrasting LOCAL shelf with quota-consuming platform searches.

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?

Explicitly routes the agent: 'Prefer cps_smart_search for "help me buy X" asks; use this for simple lookups.' This gives both the alternative and the condition that selects it, which is exactly what an agent needs to choose between overlapping search tools.

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