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

Annotations already declare destructiveHint=true, idempotentHint=true, and openWorldHint=true, so the safety profile is covered. The description adds meaningful behavioral context beyond that: the lasting effect on future scan ranking and the cost ('Free'). It stops short of stating reversibility (can the hide be undone?), which would complete the picture.

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 short clauses, action front-loaded, then effect, then cost. No waste; every element carries 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?

For a low-complexity single-param tool whose annotations cover safety, the description conveys action, side effect, and cost. But with 0% schema coverage and an ambiguous 'findId', the definition leaves the agent unsure exactly what identifier to pass and whether the action is reversible.

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 0% for the single required parameter 'findId', and the description says nothing about it. The name 'findId' is opaque (is it a thread id, a find-scan id?), so the description fails to compensate for the coverage gap in the one area an agent most needs to get right.

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 names a specific action ('Hide a thread') and a concrete secondary effect ('teach later scans to rank similar threads lower'), which makes the intent distinguishable from listing/scanning siblings. However, it doesn't explicitly name which sibling it contrasts with or clarify the 'not relevant' vs. other thread dispositions.

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?

Usage is only implied through the effect statement ('teach later scans to rank similar threads lower'), which hints at when you'd use it. There is no explicit when-to-use, when-not-to-use, or named alternative among the many conversation siblings.

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