Preview final metadata

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

The readOnlyHint and openWorldHint annotations already establish that nothing is mutated, but the description adds genuinely useful behavior beyond them: no API call is made and no quota is consumed, which matters for a quota-metered platform. It does not describe the shape of the report returned (e.g., per-field limit violations or chapter-rule warnings), which is the main behavioral unknown left.

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 compact sentences with the primary outcome front-loaded and the no-side-effect guarantee second. Nothing is redundant or padding.

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 an 11-parameter, read-only tool with no output schema, the description explains the transformation and validation intent but not what the preview actually returns or how violations are surfaced. The annotations carry the safety profile and the schema carries most parameter semantics, so the gap is narrow but real.

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 82%, so the schema already documents nearly every parameter including enums and max lengths; baseline 3 applies. The description's only added meaning is that the metadata shown is post-template application (template adds title format, footer, tags, hashtags, playlists), which clarifies how the template parameter interacts with the other fields.

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?

"Show exactly what would be sent to YouTube (title, description, tags, playlists) after applying a template" is a specific verb plus resource, and the dry-run framing plus "No API call" separates it from write-side siblings like update_video or generate_metadata. It stops short of naming any sibling outright, so the distinction is inferable rather than explicit.

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 framing implies the natural use case (validate a template-applied metadata set before committing), but the description never states when to use this versus generate_metadata or update_video. There are no explicit exclusions or prerequisites, leaving the agent to infer the preview-before-write workflow.

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