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

Annotations already mark readOnlyHint=true, and the description confirms a read-only 'Returns' operation without contradiction. The description adds valuable behavioral context beyond annotations: daily update frequency, the list of output components (trend, confidence, top_drivers, etc.), and the meaning of the score. It does not disclose any unusual caveats, but for a read-only indicator this is sufficient.

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 information-dense yet concise: it packs the metric definition, interpretation, output fields, use cases, and update frequency into two sentences plus a short update note. Every clause serves a purpose, 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?

There is no output schema, so the description compensates by naming the key output fields (trend, confidence, top_drivers, tmd_raw, upper/lower tail means) and explaining the score's interpretation. It also covers update frequency and use cases. Minor gap: the optional 'days' parameter and Gold tier behavior are only in the schema, not the main description, but the schema adequately handles that.

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 100% for the single optional 'days' parameter, and the schema description thoroughly explains its purpose, constraints, and tier requirement. The main description does not mention the parameter at all, so it adds no additional semantic value beyond the schema. Baseline 3 applies.

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 a daily 0-100 return-asymmetry score for US equities, specifies the exact computation (SPY 60-day returns, 90th-percentile upper-tail mean minus 10th-percentile lower-tail mean), and explains interpretation (50=symmetric, >50=upside skew). This provides a specific verb and resource, effectively distinguishing it from generic sibling 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?

Explicitly provides concrete when-to-use guidance: 'Call when the user asks about return skewness, tail risk asymmetry, fat tails, or non-linear return dynamics, or when timing factor rotations...' This is clear context, though it does not mention when-not-to-use or alternative tools by name.

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