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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive, closed-world). The description adds genuine behavioral context beyond that: universe size (~1,100 stocks, ~480 ETFs) and end-of-day cadence, which tells the agent not to expect intraday data. It stops short of describing pagination or rank-tie behavior, so 4 rather than 5.

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?

Two sentences: the trigger condition and examples are front-loaded, the exclusion clause trails. No filler, every clause carries selection-relevant information.

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?

With an output schema present, return values need no explanation. The description supplies scope, universe, data cadence, and boundaries, which is everything an agent needs to decide to call this over its three siblings.

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 description coverage is 67%, so the schema documents most parameters including the metric enum and the risk-sorting hint. The description contributes sector/category examples through its sample queries but adds no syntax or unit detail beyond what the schema already provides, matching the baseline 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?

States a specific verb and resource (ranked list of US stocks or ETFs by performance/risk metric) and immediately contrasts with siblings by ruling out fundamentals, news, and recommendations. An agent can distinguish this from compare_securities and get_security_metrics without opening any schema.

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?

Opens with an explicit 'Use this when...' condition plus three concrete example queries, and closes with an explicit 'Not for...' exclusion list. When-to-use and when-not-to-use are both spelled out.

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