inspect_vast

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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is clear. The description adds valuable context beyond annotations: it details the exact data returned (media files, validation issues, etc.) and notes that max_depth defaults to 5 per IAB recommendation. It does not contradict annotations; 'fetching and validating' is a read operation. No rate limits or error handling are mentioned, but given the annotations cover safety, this is adequate.

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 a single paragraph but is well-structured: it leads with the core action, enumerates the return fields, states explicit use cases, and ends with the default note. While the list of return fields is lengthy, it is informative and earns its place. It is not tautological or verbose, though it could be slightly more compact.

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?

The tool is moderately complex (follows wrapper chains) and has an output schema (not shown, but presence indicated). The description covers what it returns, how to invoke it (via URL and max_depth), and when to use it. It does not mention error handling or authentication, but these are likely covered by the output schema or are implicit. The description is sufficiently complete for an agent to call it correctly.

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?

The input schema has 100% description coverage for both parameters (url and max_depth), so the schema already explains them fully. The description repeats the max_depth default ('max_depth defaults to 5 per IAB recommendation') and adds context about the chain (e.g., 'first VAST tag'), but does not add meaningful information beyond what the schema provides. Per the rubric, a score of 3 is baseline when schema coverage is high.

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 ('Follow...'), a specific resource ('VAST wrapper chain'), and the precise action ('fetching and validating every hop'). It explicitly lists what it returns (AdSystem, AdTitle, Duration, etc.), which distinguishes it from sibling tools like validate_vast (which likely only validates) or fix_vast (which fixes). The use-case sentence ('Use this to debug wrapper chains...') reinforces its unique role.

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 use cases: 'Use this to debug wrapper chains, verify creative assets, or analyse a full ad delivery path.' It implies when to use this tool over siblings (for inspection/analysis rather than pure validation or fixing), though it does not explicitly name alternatives or state when NOT to use it. That is a minor gap, but the guidance is unambiguous enough for an agent to select it correctly.

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