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

Annotations already declare readOnlyHint=true, destructiveHint=false, and openWorldHint=false, so safety is covered. The description adds genuinely new behavioral context: the 2–12 symbol operating range and the fact that each company's fundamentals come with a stated date and basis, which tells the agent the figures are point-in-time and comparable.

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, zero filler, with the returned measures and the cardinality bound front-loaded before the usage trigger. Every clause carries information an agent can act on.

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 carries the return burden and does it: it enumerates the compared measures and notes the date/basis provenance. The single parameter is fully specified in the schema, so nothing needed to call this correctly is missing.

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% and minItems/maxItems already enforce the 2–12 bound, so the description's '2 to 12 companies' is confirmatory rather than additive. It does not clarify accepted symbol formats (ticker vs. name) or that names are resolved, so the baseline 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?

States a specific verb+resource ('Returns 2 to 12 companies side by side') and enumerates the measures compared (price move, market cap, revenue/growth, margins, price/sales, trend). The multi-symbol scoping clearly separates it from the single-company get_company and the criteria-driven screen_companies.

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?

Gives an explicit trigger — 'Use it when the user asks to compare companies' — so the agent knows the intent that selects this tool. It stops short of naming alternatives (e.g., screen_companies for criteria-based discovery or get_company for a single name), so there are no stated exclusions.

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