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

Annotations already establish read-only, idempotent, open-world, non-destructive behavior. The description adds two genuinely non-annotated facts: the fields each record carries and the pricing model ('5 points per returned record'), which is valuable for cost-aware planning. It says nothing about pagination, rate limits, or how video/short/stream result sets are combined.

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?

Two dense sentences that front-load the core operation and keep the field list and pricing note compact. The long comma-separated field enumeration is load-bearing (there is no output schema), though it is the one place that reads as a dump.

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 12-parameter tool with no output schema, the description does cover what comes back per record and the credit cost. It leaves open how the three result-type caps combine and what happens when a filter is omitted, which matters for correct invocation.

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 all 12 parameters including the six enums are already documented with their options and defaults. The description only loosely echoes the filter families (upload date, type, length, features) without clarifying the interaction between max_results, max_results_shorts, and max_results_streams, so it adds little beyond the schema.

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 verb and resource ('Search YouTube videos, shorts and streams by keyword') and enumerates the filter dimensions and returned fields, so the agent knows exactly what it does. It does not distinguish itself from the sibling run_youtube_shorts, which overlaps with the 'shorts' part of this scope.

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 implies keyword-driven discovery but never says when to choose this over run_youtube_shorts, run_youtube_channel, or run_youtube_comments. There are no exclusions, no prerequisites, and no routing guidance for an agent facing four YouTube siblings.

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