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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the safety profile is covered. The description adds real behavioral context beyond that: the cost ('1 credit') and the fact that the payload can be either profile metadata or a video list depending on include_posts. It does not mention rate limits, auth, or pagination for the posts mode.

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?

A single semicolon-linked sentence that front-loads the resource and what is returned, then the mode flag, then cost. No filler; every clause adds information an agent would otherwise have to guess.

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 compensates by enumerating the profile fields and noting the alternate video-list return shape. For a two-parameter read tool this is close to complete, though post-mode details such as count or pagination are left unstated.

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 0%, so the description must carry the parameter burden, and it largely does: unique_id is explained as a username lookup and include_posts is explained as a mode switch to latest videos. It omits formatting details for unique_id (e.g., whether the '@' prefix is accepted).

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 resource and retrieval mode: a TikTok profile keyed by username, enumerating the returned fields (bio, counts, verified badge, numeric user id). It also distinguishes the include_posts mode as returning videos instead. It doesn't explicitly name sibling tools like tiktokVideo or tiktokSearch, so differentiation is partial rather than crisp.

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 clause 'include_posts returns the latest videos instead' gives one concrete usage switch between two modes of this tool. However, there is no guidance on when to prefer this tool over siblings such as tiktokSearch, tiktokVideo, or tiktokFollowers, so selection context is only implied.

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