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

With no annotations, the description carries the full burden, and it does disclose two things structured fields cannot: the data-source population limit and the methodological caveat that a delta can reflect members joining rather than prices moving, with a concrete instruction to compare members_at_start with members. It does not state auth requirements, rate limits, or return format, which keeps it short of 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?

Two sentences, front-loaded with what the data is, then the caveat. The first sentence is dense with scope qualifiers but every clause adds real meaning; no filler or restatement of the title.

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 an aggregation tool with no output schema, the description usefully names key return fields and the interpretive caveat, but it omits any explanation of the 'days' window (including the 9999 value), pagination, and the shape of the time series. An agent can call it, but not confidently reason about what it gets back.

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?

There is one parameter, 'days', with 0% schema description coverage, and the description never mentions it. The enum includes a non-obvious 9999 all-time sentinel that goes unexplained, so the description fails to compensate for the coverage gap. The output-field names it references (members_at_start, members) are returns, not parameters.

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?

The description states a specific resource and scope: combined Classic and UGC value at RAP plus copies held across all public portfolios on the RBX Invest players board, tracked over time. The 'history' framing implicitly separates it from snapshot siblings like get_community_holdings and get_player_holdings, though it never names them explicitly.

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?

Scope is clarified ('RBX Invest members who linked a Roblox account, not all of Roblox'), which tells the agent what population the data represents. However, there is no explicit when-to-use guidance and no named alternative for snapshot-vs-trend queries, so the routing is left to inference from the name.

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