get_etf_overlap

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

With no annotations, the description carries the full burden and does well: it reveals the data source, the exact nature of the output, and the dependency that SEC_USER_AGENT must be set to a name and email. It does not mention rate limits or potential failures, but the disclosed auth and data-source context is substantial.

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 sentences, each earning its place: the core result, the concrete use case, and the required environment variable. The most important information is front-loaded and there is no filler.

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-parameter tool with no output schema, the description is complete: it states what the tool returns, why someone would use it, and what setup it needs. An agent has enough to select and invoke it correctly without additional inference.

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%: the schema already documents symbols as exactly two ETF tickers with an example. The description adds no meaning beyond restating that two ETFs are involved, so the baseline of 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?

The description clearly states the tool computes how much two ETFs hold the same things, names the data source (full SEC N-PORT holdings), and enumerates the outputs (weighted overlap, shared count, biggest shared positions). This distinguishes it from the sibling tools like get_etf_holdings or compare_etfs and makes the resource and verb unambiguous.

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?

"Use it to check whether owning both actually diversifies" provides a clear, concrete context for when to call this tool. It does not explicitly name alternative tools or give when-not-to-use exclusions, so it stops one step short of full guidance.

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