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

With no annotations provided, the description carries the full burden of behavioral disclosure. It discloses a meaningful side effect: 'Costs 1 credit per search.' It also states what the response includes (titles, ids, URLs). It stops short of detailing pagination or result ordering, but for a simple keyword search this is sufficient to prepare an agent.

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 sentences with no wasted words. It front-loads the core action and scope, then provides return information, use cases, and cost. Every clause earns its place; the cost disclosure is especially valuable to surface early.

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 tool with three parameters, no output schema, and no annotations, the description covers the essential invocation context: what to search, what to expect back, and the cost. The only minor gap is that it does not explicitly mention the default type (video) or hint at how results vary by type, though the schema already covers the default.

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 100%, so the baseline of 3 applies. The description adds the phrase 'set type' which maps to the type parameter, and 'by keyword' clarifies query usage, but these are already evident from the schema. The limit and default behavior are fully documented in the schema, so the description adds no significant semantic value.

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 and resource ('Search YouTube by keyword') and explicitly enumerates the retrievable object types ('videos, channels, or playlists'). It also names the return fields (titles, ids, URLs), making the tool's function distinct from siblings like get_channel_videos or get_transcript, which have different retrieval logic.

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 clear application context ('useful for research, discovery, and finding videos to transcribe'), which helps an agent decide when this tool is appropriate. However, it does not explicitly mention alternatives or exclusion conditions, such as reserving get_latest_videos for recency-based needs or get_playlist_videos for playlist-browsing.

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