Check how far you have read

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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false, covering the safety profile. The description adds valuable context beyond annotations: the read position is shared across every client on the account, and the returned id is a meaningful opaque token for incremental fetching. This enriches understanding without contradicting the hints.

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 two sentences with no wasted words. The first sentence defines the resource and its scope, the second gives actionable guidance on using the result. Information is front-loaded and 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?

For a simple read-only tool with one optional parameter and rich annotations, the description is complete. It explains what the return value represents, how it behaves across clients, and how to use it in downstream calls. There is no output schema, but the description sufficiently conveys the value's purpose. Missing edge cases (e.g., no read position yet) are minor given the tool's simplicity.

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 single parameter 'account' has full description coverage in the schema (100%), including its matching behavior and default. The description itself adds no parameter-specific details, but the baseline of 3 applies because the schema fully documents the parameter.

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 clearly states a specific verb ('check how far you have read' from the title) and resource ('last notification and home-timeline entry you marked read'), and explicitly distinguishes its output's purpose ('Pass the returned id as since_id'). This differentiates it from siblings like mark_read or get_home_timeline.

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 provides explicit instructions on how to use the returned value ('Pass the returned id as since_id to fetch only what is new'), giving clear practical guidance. However, it does not explicitly state when to use this versus alternatives (e.g., mark_read for setting the position), though the usage is strongly implied.

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