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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the description is not required to re-explain safety from scratch. It adds value by clarifying that this is an external API call, stating the return shape (array of matching users), and noting the default and maximum result count. No contradiction with annotations.

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 compact and front-loaded: the core purpose appears in the first sentence, followed by clear use/not-use guidance, an optional-performance note, and return limits. Each sentence earns its place, with minimal redundancy even though the final 'safe, read-only' sentence partly overlaps annotations.

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 search tool with no output schema, the description covers the essential contract: query input, optional field filtering, return shape, count limits, and when to avoid the tool. It does not elaborate on error handling or rate limits, but the required information an agent needs to invoke it correctly is mostly present.

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 63%, so the schema carries most of the parameter semantics itself. The description adds a helpful high-level note that the `fields` parameter is a performance optimization and restates the default fields, but it doesn't substantially elaborate on parameters like `name` or `userPrompt` beyond what the schema already says.

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 states a specific verb ('Search'), a specific resource ('TikTok users'), and a scope ('by name or username'). It explicitly contrasts with exact username lookup and directs the agent to getTiktokUser, making sibling differentiation clear even before opening the schema.

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?

The description provides explicit 'Use for' and 'NOT for' guidance, lists concrete use cases like finding multiple candidates and fuzzy matching, and names the alternative tool to use when an exact username is known. This leaves no ambiguity about when to select this tool.

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