wb_sources

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, so the safety profile is covered. The description adds useful behavioral context: the ~70 sources count and the fact that providing source_id changes the output from sources to indicators. However, it doesn't disclose details like pagination, response format, or what happens with an invalid source_id, which would be valuable for a browse 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?

Two sentences with zero waste. The primary purpose is front-loaded, and the conditional behavior is explained efficiently. Every sentence earns its place.

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 simple browse tool with one optional parameter, the description is nearly complete. It explains both modes and gives a concrete example. The only minor gap is the lack of detail about the response shape or error behavior, but given the tool's simplicity and the annotations covering safety, this is a minor omission.

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%, so the schema already documents the single parameter. The description adds a concrete example ('2' = World Development Indicators) and clarifies the omit-vs-provide behavior, which is helpful. However, since the schema already covers the parameter fully, the description's added value is modest, warranting the baseline 3.

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 uses a specific verb ('Browse') and a clear resource ('World Bank data source databases'), and explicitly distinguishes the two modes: listing all ~70 sources when source_id is omitted, or listing every indicator in a specific database when source_id is provided. This makes the tool's purpose unambiguous and differentiates it from siblings like wb_indicator, wb_compare, and wb_search.

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 clearly states when to use the tool (to browse sources or indicators) and explains the two invocation modes. It doesn't explicitly name alternative tools or state when not to use it, but the context is clear enough for an agent to select it appropriately among the World Bank siblings.

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