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

Annotations already cover the safety profile (readOnlyHint=true, destructiveHint=false, openWorldHint=false), and the description adds genuinely new behavioral context: data coverage starting 2 Jan 2020, the default descending date ordering, unit semantics per field, and which values are computed (changePercent, foreignNet). It stops short of rate limits, auth, or pagination caveats.

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?

Three short paragraphs, each front-loaded: purpose first, then units, then return shape. The unit list is dense but every clause carries information an agent needs to interpret the numbers, so little is wasted.

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 burden of describing returns and does so explicitly ({ data, total, page, limit }), plus per-field units, computed-field formulas, and the data start date. That is sufficient for an agent to call and interpret the result correctly.

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 only 50% (page, limit and sortOrder carry no descriptions), so the description should compensate more than it does. It contributes a real constraint via 'Data starts 2 Jan 2020' (a practical floor for 'from') and clarifies sortOrder's default effect, but never explains page/limit paging behavior.

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 resource ('daily trading summaries') bound to a precise scope ('one IDX ticker') and enumerates the returned fields (OHLC, volume, value, trade count, best bid/offer, foreign buy/sell, non-regular activity). The per-ticker scoping implicitly separates it from Idx_market_summary and Idx_get_company.

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 never says when to prefer this tool over siblings such as Idx_market_summary, nor any prerequisites or exclusions. 'Defaults to the most recent days first' is a default value, not usage guidance about which tool to pick.

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