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

Annotations already declare readOnlyHint=true and openWorldHint=true, so the read-only nature is covered. The description adds behavioral details beyond annotations: the author identity-only limitation (no follower counts) and the credit cost ('Credits: 1 (+downloadMedia add-on)'). This gives the agent valuable information about what to expect in the response and the cost implications.

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 two concise sentences with zero waste. It front-loads the core purpose, then adds a critical limitation and cost information. Every word earns its place, making it highly efficient for an agent to parse.

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 read-only tool with a fully documented schema and no output schema, the description is sufficiently complete. It covers the main purpose, a key limitation, and cost. It does not mention that the tool can also handle photo posts (as indicated in the url schema description), but this is a minor gap given the schema covers it.

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 the schema already provides detailed descriptions for all 5 parameters (url, trim, region, downloadMedia, getTranscript). The description does not add any parameter semantics beyond what the schema provides. The mention of downloadMedia credits in the description is also already in the schema description, so no extra value is added.

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 exactly what the tool does: 'Get a single TikTok video by URL.' It clearly identifies the resource (video) and the input (URL), and immediately distinguishes itself from sibling tools like tiktok_profile_get by noting that author data is identity-only (no follower counts). This prevents confusion with profile-oriented tools.

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 explicitly tells the agent when NOT to use this tool: 'use tiktok_profile_get for metrics.' This is a clear alternative. However, it does not mention other sibling tools like tiktok_video_download_get for downloading or tiktok_video_transcript_get for transcripts, which could be relevant. Still, the primary alternative is covered and the context is clear.

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