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

Annotations already declare readOnlyHint, idempotentHint, and destructiveHint, but the description adds valuable behavioral context beyond them: reading does not consume items, items repeat until expiry, and a lost response loses nothing. It also reinforces the closed-world scope consistent with openWorldHint false. This is exactly the kind of transparency that helps an agent predict side effects.

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?

The description is three purposeful sentences with no filler. It front-loads the core purpose, then adds exclusions, and closes with pagination guidance. Every sentence earns its place.

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?

Given an output schema and rich annotations, the description is fully complete for invocation: it defines the item scope, excludes unrelated phone data, explains non-destructive repeated reads, and explains pagination with the cursor. Nothing an agent needs 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?

Schema coverage is 100%, so the parameter names, ranges, and defaults are already documented. The description adds practical meaning to `since` by explaining that returning the cursor yields only new items. This goes beyond the schema's 'Opaque cursor from a previous call' and justifies a score above the baseline.

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 and resource: 'Read items the user deliberately shared from their phone to you' via 'Share to Agents'. It actively excludes text messages, notifications, and other phone data, making the tool's scope unmistakable. This clearly distinguishes it from siblings like check_reply or find_my_phone.

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 gives clear context on what to use it for and explicitly what not to use it for: 'This does NOT read their text messages, their notifications, or anything else on the phone.' It also explains cursor reuse by instructing the agent to pass the returned cursor back as `since`. It does not name a sibling alternative, but the exclusions are strong enough to guide selection.

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