explain_widget

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

No annotations are provided, so the description carries the full burden of disclosure. It makes clear this is a read-only explanatory operation scoped to the local index, which implies no mutation. However, it doesn't state what happens when a widget is not found in the index, whether reindexing is a prerequisite, or what the response structure looks like.

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?

One sentence, zero waste. The parenthetical list of explanation dimensions adds value without bloat. It is appropriately brief, though it could be marginally more informative without becoming verbose.

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 seemingly simple read-only explain tool with no output schema and no annotations, the description is adequate but thin. It doesn't mention the return format (text? structured?), behavior for unknown widgets, whether the 'repository' parameter is needed, or prerequisites like index freshness. Given the low complexity, this is minimally viable but leaves gaps.

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 coverage is 50%. The required 'name' parameter is described as 'Widget class name' in the schema, and the description reinforces this by specifying the widget is looked up in the local index. However, the 'repository' parameter has NO schema description and the tool description doesn't clarify its meaning, purpose, or whether it's optional scoping.

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 verb ('Explain') and resource ('a widget from the local index') with parenthetical detail on dimensions (declaration, inheritance, documentation). This clearly distinguishes it from sibling tools like find_widget (finding) and trace_widget (tracing inheritance/usage), though it doesn't explicitly name alternatives.

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 phrase 'from the local index' implies the tool only works on widgets that exist locally and is not used for external searches. However, there is no explicit when-to-use vs. when-not-to-use guidance, nor naming of alternatives. The context of 'local index' vs. live-source tools like search_source is implied but not stated.

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