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

Annotations already declare readOnlyHint, idempotentHint, non-destructive, and closed-world behavior, so the safety profile is covered. The description adds useful context: the source is Yahoo Finance via yfinance and no API key is required, plus it reiterates that the tool only works for ETFs and mutual funds.

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 description is front-loaded with purpose and then structured into useful bullets. It is slightly longer than strictly necessary, but every block contributes to selection or invocation.

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-value explanation is not required. The description covers the tool's scope, section choices, data source, and stock alternative; remaining gaps are mostly auxiliary filtering parameters that the schema documents.

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 description clarifies the section options and gives practical examples for holdings, sectors, and bond ratings, which helps with the primary fund-profile parameters. However, it does not add meaning beyond the schema for the many auxiliary parameters such as wholesaler_ids, source_resource_id, exclude_fillers, or optional_additional_filters; the schema itself carries that detail.

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 ('Fetch ETF or mutual fund specific data') and enumerates the exact data categories returned. It also explicitly distinguishes the tool from GetTickerInfo by limiting scope to ETFs and mutual funds.

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?

Provides an explicit 'Use this tool when' list covering holdings, sector allocation, bond ratings, and fund-profile comparisons. It also names the alternative for stocks ('For stocks, use GetTickerInfo'), leaving little ambiguity about when to select this tool.

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