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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, so no safety warning is needed. The description adds meaningful behavioral context beyond those flags: the response includes grid_cols and size_bounds, there is no preset chart type, and size_bounds apply per type rather than per catalog_id. This is exactly the kind of non-obvious behavior an agent needs to know.

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 dense paragraphs, each earning its place. The first identifies the resource and the critical limitation (no preset charts). The second explains the useful response fields and how to use them. It is longer than a one-liner, but every sentence adds operational value and the core purpose is front-loaded.

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?

Even without an output schema, the description covers the return payload's relevant fields: catalog_id, the supported kpi/widget types, grid_cols, and size_bounds. It also gives the cross-reference to create_dashboard for custom_chart specs. Nothing essential is missing for an agent to call the tool correctly and interpret its results.

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 tool has zero parameters, so the description needs to add nothing about inputs. The empty schema fully covers parameter semantics. The description instead usefully explains what the catalog entries reference and how the response fields should be consumed.

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 opens with a specific verb and resource: 'List the built-in ("preset") dashboard widgets available to place with create_dashboard/set_dashboard_widgets.' It clearly distinguishes this catalog from the sibling list_dashboards by framing it as a widget catalog rather than a dashboard list, and it further separates preset entries from custom charts.

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?

It explicitly explains when this tool should be used: to find preset widget catalog_ids before calling create_dashboard/set_dashboard_widgets. It also names the alternative for trend charts ('build one inline with a {"kind": "custom_chart", ...} spec instead of a catalog_id') and tells the agent to consult grid_cols and size_bounds before supplying explicit w/h values.

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