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

Annotations already declare readOnlyHint=true, openWorldHint=false, and destructiveHint=false, so the safety profile is covered. The description adds meaningful behavioral context beyond annotations by detailing the lifecycle values, the notion of a live 'current' revision, and the 'dark' state caused by edits after approval. It does not contradict the annotations.

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 with no filler. The first sentence front-loads what the tool returns, and the second gives a concrete diagnostic use case. Every clause adds useful information.

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?

The tool has a single required parameter, safe read-only annotations, and an output schema that can carry the return-structure details. The description provides the diagnostic scenario, explains the meaning of 'dark', and covers all state categories an agent needs to decide whether to call this tool. Nothing essential 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 description coverage is 100% and thread_id is adequately documented as 'XenForo thread ID'. The description reinforces that it targets 'one article thread' but adds no essential parameter semantics beyond the schema, so the baseline of 3 is appropriate.

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 ('Get'), a specific resource ('Key-Facts supplement state for one article thread'), and enumerates the exact facets of that state: lifecycle status, current-revision flag, and sidebar rendering/dark/absent. This clearly differentiates it from broad list/search siblings like list_drifted or get_thread.

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 tells the agent when to use it: 'Use to answer "why is there no Key-Facts card on thread N?"'. This is a clear invocation context, though it does not explicitly state when not to use it or name alternative tools for comparison.

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