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

Annotations already cover the safety profile (readOnly, idempotent, non-destructive), so the bar is lower, and the description adds real context: the exact semantics of undervalued/overvalued/near_fair_value/no_valuation thresholds, that values cannot be derived from other fields, and that it is a valuation rather than financial advice. It does not mention rate limits or caching, which is the only notable gap.

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?

Front-loaded with purpose and routing, which is good, but the deep_link content is stated twice — once in the field list and again in the closing sentence 'deep_link opens the full analysis page with the fair value history chart and every valuation model.' That redundancy costs a point for an otherwise dense paragraph.

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 no output schema, the description carries the return-value burden and does explain every field (valuation_status, upside_band, quality_score, evidence_level, deep_link) plus band formats. It is sufficiently complete for an agent to call and interpret the result, though there is mild overlap with the sibling link semantics typical of this tool family.

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 there is only one parameter, so the schema already fully documents symbol format and fallback resolution. The description adds nothing about the symbol parameter, so the 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?

States a specific verb+resource ('snapshot for one stock') with scope ('without the exact fair value') and explicitly names the sibling it is not (get_stock_verdict). An agent can distinguish it from compare_stocks and screen_stocks without opening a 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?

Gives an explicit when-to-use rule ('check many stocks cheaply') and the selecting condition for the alternative ('use get_stock_verdict when the user wants the actual fair value'). No inference required.

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