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

With no annotations, the description carries the full burden and does disclose the return encoding: market-local hhmm begin/end times plus a trade_session code mapped to regular/pre-market/after-hours/overnight. That is genuinely useful behavioral context and compensates for the absent output schema. It stops short of stating timezone handling details or whether schedules vary by date.

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 the tool's purpose, then the return-value convention in two compact lines. The inline enumeration of session codes is dense but earns its place since no output schema exists. Minimal waste.

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?

For a single-optional-parameter lookup with no annotations and no output schema, the description supplies the return format, value semantics, and the all-markets default, which is largely sufficient. Date/range behavior and any calendar dependency are the only notable omissions.

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% and the single market parameter is fully documented in the schema (uppercase US, HK, or CN; omit for all). The description adds only the same all-markets behavior, so 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 and resource — retrieving trading session schedules per stock market — and clarifies the scope is one market or all. It does not, however, differentiate itself from similar siblings such as get_market_status or get_trade_days, leaving the agent to infer the boundary.

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 implies usage by noting the market parameter can be omitted for all markets, and the schema repeats this. There is no explicit when-to-use or when-not-to-use guidance relative to sibling tools like get_market_status or get_trade_days.

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