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

Beyond the annotations (only openWorldHint), the description reveals that the tool returns a merged text of multiple categories, applies a 'last two years' time filter, and explicitly states exclusions. These behavioral traits are valuable for agent decision-making and are not covered by the annotation.

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 structured with bullet-like lists for indicators, exclusions, and typical questions, making it skimmable. It includes pricing info that might be redundant but not harmful. It is slightly verbose but each sentence adds context; 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?

Given the presence of an output schema and the tool's moderate complexity, the description adequately explains what is returned (merged text with three categories) and what is excluded. It does not detail output formatting, but the output schema covers that. For a list tool with clear scope, the description is complete enough.

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 schema covers 100% of parameters, providing baseline 3. The description adds value by giving concrete examples for region (national, provincial, municipal, district) and chain names, and implicitly clarifies that the 'year' parameter determines the end of the two-year window. This exceeds the schema's basic descriptions.

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 queries a list of companies that made external investments in the last two years, filtered by region and chain name, and returns a merged text covering total, production, sales, and dependent types. It explicitly distinguishes from count-only tools and other classification filters, making its purpose specific and non-overlapping with siblings.

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 provides typical question examples and lists what is excluded (e.g., other classifications, counts without lists), giving clear context on when to use this tool. However, it does not explicitly name alternative tools for counts or other list types, so it lacks explicit guidance on switching to siblings like chain_invest_company_num.

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