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

Annotations declare readOnlyHint, idempotentHint and closed-world, and the description adds genuinely new context beyond them: the widget is interactive, its Sync/Disconnect actions call back into 'admin', reconnect/connect-new hand off to the web app, and Plaid Link cannot run inside the MCP iframe. This delegation detail explains why the tool itself remains a read.

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?

Three tight sentences, front-loaded with what renders before routing rules. Every clause carries information: rendering contents, trigger conditions, callback targets, and the iframe constraint.

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?

With no parameters and no output schema, the description must carry the full burden of what to expect and when to use it, and it does: it describes the rendered widget, its interactive actions, and where mutating behavior is delegated. Nothing an agent needs to select or invoke it is missing.

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 has zero parameters, so the baseline is 4 with no param semantics needed. The description correctly implies the widget is invoked without arguments.

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?

Names a specific verb and resource ('Show the user's connected banks and accounts as an interactive dashboard widget') and enumerates exactly what renders (institution cards, sync status, last-sync timestamp, accounts, actions). It is unmistakably distinct from the sibling tools admin and query.

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?

Gives explicit when-to-use ('whenever the user asks to see, manage, sync, reconnect, or disconnect') and explicit when-not-to-use, routing text status to admin { entity: 'bank_connection', action: 'list' } and balances/activity to query { account_summary: true }. Nothing is left to inference.

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