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

Annotations already declare readOnlyHint=true, and the description adds valuable context: the index scale (0-100, 50=baseline), the exact inputs (editing activity vs pageviews), update frequency ('Updates: daily'), and the delivered fields (score, trend, top_drivers, confidence, freshness, methodology_version). This goes beyond the minimal read-only flag and gives the agent a clear expected behavior, though it omits details like auth requirements or rate limits (likely unnecessary here).

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 concise and well-structured: the first sentence encapsulates the metric definition, scale, and output fields; the second sentence provides use cases and update frequency. Every sentence carries information, with no filler or redundancy.

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 read-only data retrieval tool with one optional parameter documented in the schema, the description supplies all necessary context: the index's meaning, what it measures, what it returns, when to use it, and its update cadence. The absence of an output schema is compensated by explicitly listing the returned fields. The tool is self-contained and easy to invoke 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 the single optional 'days' parameter, so the description does not need to restate it. Per the rubric, a baseline of 3 applies when schema coverage is high. The description does not add any extra parameter semantics, which is acceptable given the schema already fully explains the history behavior and Gold tier requirement.

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 clearly states what the tool does: 'Returns a 0-100 global knowledge-production index' with a precise definition (worldwide daily edits + active editors vs trailing 180-day baselines). It distinguishes itself by specifying 'editing activity, not pageviews' and naming the tool's focus, making it distinct from generic index tools.

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 explicit when-to-use guidance: 'Call when the user asks about Wikipedia editing velocity, encyclopedic knowledge growth, or open-knowledge community health, or when timing corpus refreshes, dataset snapshots, or knowledge-base sync runs.' However, it does not mention when not to use it or name alternative tools, so it falls short of a 5.

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