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

Annotations provide readOnlyHint=false, openWorldHint=true, and idempotentHint=true, but the description adds critical behavioral details: it returns immediately without waiting, opens a browser or shows a device code, and requires the agent to relay the URL/code verbatim. This exceeds annotation context and helps the agent manage user interaction.

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, front-loaded with purpose, followed by behavior and usage instruction. Every word earns its place; no redundancy or filler.

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 initiation tool with no output schema, the description fully covers what the agent needs: return behavior, asynchronous nature, and user action required. It also links appropriately to sibling authStatus for follow-up, making the tool's context complete.

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 and the schema coverage is 100% (empty properties), so the description has no responsibility to document params. The baseline of 4 is appropriate since there is nothing to add.

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+resource: 'Begin sign-in to the Microsoft account that owns the OneNote notebooks.' It clearly distinguishes the tool's role from siblings like authStatus (which checks status) and signOut (which ends sessions).

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 explicitly says 'poll authStatus afterwards to confirm' and instructs to 'Always show the user the returned URL and code verbatim,' providing clear usage guidance and implying that this tool is for initiation, not status checking. It also notes the tool returns immediately, so the agent knows not to wait.

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