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

Annotations already declare readOnlyHint=true and openWorldHint=false, so safety is covered. The description adds genuinely useful non-schema behavior: the cost of one request unit and that the whole exchange is returned unless symbols narrows it. It does not mention rate limits or failure modes, keeping it below a 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?

Three short sentences with zero waste, front-loading what the tool returns before mentioning the date default, the symbols narrowing, and the cost. Every sentence earns its place.

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?

An output schema exists, so return shape needn't be explained, and the read-only safety profile is covered by annotations. For a 4-parameter tool the description is nearly complete, though it omits any mention of the 'filter' extended-fields constraint or result size expectations.

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 100%, so the schema already documents date, filter, symbols, and exchange. The description restates only the symbols and date semantics in slightly different words, adding no format, boundary, or interaction detail beyond what the schema provides.

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+scope: one OHLCV bar per listed instrument on an exchange for a trading day, with the latest-session default. However, it never contrasts itself with siblings such as 'prices', 'market_cap', or 'ai_market', so an agent must infer which market tool applies.

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 one concrete usage rule ('Omit date for the latest session') and the cost, but offers no when-to-use vs alternatives guidance. The sibling set is large and related (prices, market_cap, benchmark), yet none are mentioned as alternatives or exclusions.

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