get_market_index

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

No annotations are supplied, so the description carries the full behavioral burden, and it does disclose useful traits: realtime cadence, a fixed index universe, and the upstream data source (Sina Finance). It omits whether quotes may be delayed, whether the call can fail on network/source outages, and whether the fixed four-index list can be extended – gaps that matter for a network-backed quote tool.

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?

The Google-style Args/Returns layout is front-loaded with scope, then coverage, then source, then parameter and return fields – every line carries information. Minor waste in restating the return fields as a list when the return shape is apparent, but nothing is padded.

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 one-optional-parameter read tool with no output schema, the description covers scope, the exact index universe, the data source, the single parameter's enum values and default, and the returned field names. Only failure modes and freshness guarantees are missing, which is a modest gap given the tool's simplicity.

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?

The single 'format' parameter is undocumented in the schema (0% coverage) but the description fully compensates: it names the three accepted values 'markdown' | 'json' | 'csv' and states the default of 'markdown'. That is more than the schema provides and is enough to call the tool correctly.

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 ('Fetches realtime market index data') and enumerates exactly which indices are covered (上证指数, 深证成指, 创业板指, 科创50), which lets an agent distinguish it from the stock-quote siblings such as get_realtime_quote. It stops short of naming an alternative tool outright, so it is clear but not fully differentiated.

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?

Usage is only implied: the description establishes this is the index-level realtime snapshot tool, so an agent can infer it is the right pick when indices (not individual stocks) are wanted. There is no explicit when-to-use or when-not-to-use statement, and no mention of get_realtime_quote, get_index_constituents, or get_realtime_multi_quote as alternatives.

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