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

Annotations already cover read-only, idempotent, non-destructive, so the safety profile is known. The description adds valuable behavioral context beyond annotations: 'a delay never overwrites the original plan', 'is_projection for forward-dated milestones', and 'Full history Pro (never a 403)' — all non-obvious behaviors an agent needs to correctly interpret results.

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 well-structured and front-loaded: a crisp definition, followed by use cases, exclusions, filters, and data shape. Each sentence adds distinct information, and the 'USE THIS'/'DO NOT USE' formatting makes it scannable. No wasted words.

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?

Without an output schema, the description explains the row structure in detail (foundry, fab_name, event_type, event_date, announced_date, summary, source URL, quote, is_projection). It also covers access levels and citation. The only notable gap is the semantics of the date-range parameters (to/from/since/all), but overall the tool is well understood.

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 0%, so the description must compensate. It does enumerate the meaningful filters (foundry, fab_id, event_type with allowed values in parentheses, country), which adds real semantics. However, it leaves to/from/since/all/limit undefined, and the difference between 'since' and 'from' is not addressed. Partial compensation warrants a 3.

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 opens with 'Fab Milestones — the dated construction & ramp event log' which clearly identifies the resource and its purpose. It goes on to list concrete event types and explicitly distinguishes from sibling tools like get_fab_capacity and get_foundry_allocation, making the tool's role unmistakable.

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 an explicit 'USE THIS for' section with concrete examples (tracking TSMC Arizona, Intel Ohio, etc.) and a 'DO NOT USE for' section naming alternative tools (get_fab_capacity for capacity, get_foundry_allocation for allocation). This is exactly the kind of when-to-use/when-not-to-use guidance the dimension calls for.

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