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

Beyond the annotations (readOnlyHint=true, destructiveHint=false), the description adds valuable behavioral context: the data source ('derived from CF analytics-engine'), privacy ('no PII'), the output shape ('just (pack, tool, count)'), and caching behavior ('Cached 5min-1h depending on window'). No contradiction with annotations.

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 four sentences, front-loaded with the core purpose, then use cases, then data provenance and caching. Every sentence adds useful information with no redundancy or fluff, though it is slightly longer than the two-sentence ideal.

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 tool with one optional parameter and no output schema, the description sufficiently covers what it returns, when to use it, data source, privacy, and caching. It does not detail the exact return structure beyond '(pack, tool, count)', but this is adequate given the simplicity of the tool.

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 already provides full description for the only parameter `window`, including its enum values and semantics about short vs long windows. The tool description merely repeats '24h, 7d, or 30d' without adding new meaning, so with 100% schema description coverage, the baseline of 3 is appropriate.

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 the tool 'Returns the top tools, top packs, and total call volume over a recent window (24h, 7d, or 30d)', providing a specific verb and resource. It is inherently distinct from siblings by focusing on trending agent calls, but it does not explicitly name an alternative tool for comparison.

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 lists three concrete use cases: 'discovering what data sources are hot for current events', 'confirming a popular tool is the canonical choice before asking your own question', and 'seeing whether your use case aligns with what most agents need'. This gives clear context for when to use it, though it lacks explicit exclusions or alternative tool suggestions.

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