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

With no annotations, the description carries the full burden. It discloses ranking behavior (relevance then download count), supported languages, and the platform source. It does not explicitly state it's read-only, but 'Search' implies this. It could mention authentication or rate limits, but for a search tool the transparency 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?

The description is packed with information but remains focused. It front-loads the main purpose and then provides useful details on directions, languages, return fields, ranking, and usage. Every sentence adds value, though the '3 main directions' sentence could be more structured to avoid ambiguity. It's concise relative to the information presented.

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?

Despite no output schema, the description lists the return fields, ranking, and usage context, which covers most essentials. The only gap is a slight ambiguity about how the '3 main directions' relate to the tool — whether it searches all three or just skills. Minor omission of rate limits or pagination, but overall complete for a search tool.

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 baseline is 3. The description adds value by explaining query supports 7 languages and provides concrete multilingual examples (e.g., 'email automation', '邮件自动化'). It also clarifies ranking behavior, which indirectly helps understand the 'limit' parameter. The schema already documents limit default and max, so this exceeds the baseline.

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 description opens with a specific verb and resource: 'Search hundreds of thousands of AI agent skills.' It clearly distinguishes the tool from siblings like search_use_cases by focusing on skills and listing the exact return fields (slug, name, description, etc.). Despite a brief mention of '3 main directions,' the core purpose is unambiguous.

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?

Provides explicit when-to-use context: 'Use when user wants to find or discover skills for a specific task or topic.' It gives multilingual example queries, but does not explicitly name alternatives or say when not to use this tool versus search_use_cases or other siblings. The guidance is clear, but lacks explicit exclusions.

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