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

Annotations already declare readOnlyHint=true, destructiveHint=false and openWorldHint=true, so the safety profile is covered. The description adds only that the response includes the widget's settings, and says nothing about error behavior for unknown ids or what 'settings' comprises, which matters since there is no output schema.

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 short fragments, zero waste, and the resource is front-loaded before the endpoint. The lead is a noun phrase rather than a verb phrase, which makes it slightly less immediately actionable than a full sentence.

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 two-parameter read with full schema coverage and a complete annotation set, the description is adequate but thin: with no output schema, it should at minimum sketch the returned widget shape, and it gives no guidance on failure for a bad id.

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%, and both parameters are documented there, including the fields projection and the 'from idx_list_widgets' provenance of widget_id. The description contributes no additional parameter meaning, so the baseline 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 names a single resource ('One JavaScript widget with its settings') and the underlying endpoint, so the agent understands it is a single-item fetch. The singular 'One' implicitly contrasts with idx_list_widgets, though it never names that sibling explicitly.

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?

There is no statement of when to use this tool versus idx_list_widgets or any other sibling. The only routing hint, that widget_id comes from idx_list_widgets, lives in the schema rather than the description.

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