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

Annotations already declare idempotentHint=true and destructiveHint=true, lowering the burden. The description adds genuinely new behavior beyond them: featuring is exclusive (one featured link) and passing null clears the current feature, which is the key state-change an agent must anticipate.

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?

A single sentence, front-loaded with the primary effect and the exceptional null case parenthetically. Every clause earns its place with no redundancy.

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 one-parameter mutation with no output schema and annotations covering safety and idempotency, the description supplies purpose and the null semantics. Only minor gaps remain, such as which page is affected and whether a prior featured link is replaced silently.

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 0% for the nullable link_id (only the string branch has a short description), but the description explicitly defines the null branch ('features none'), which the schema leaves undocumented. That compensates well for the coverage gap.

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?

States a specific verb+resource ('Makes one link the page's featured link') and covers the clearing case, so an agent can distinguish it from update_link or reorder_links. It does not explicitly name those siblings, so it falls just short of a 5.

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: the tool's name and purpose suggest when to call it, and the null case hints at how to unfeature. There is no statement of when to prefer this over update_link, nor any prerequisites or exclusions.

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