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

Annotations already declare readOnlyHint=true and destructiveHint=false, so the safety profile is covered. The description adds that labels are for 'tagging posts and media,' which is useful context, but it does not disclose additional behaviors such as pagination, ordering, filtering semantics, or return format.

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 short sentences with no wasted words. The purpose is front-loaded, followed by a clear usage cue, and every sentence contributes to understanding.

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 listing tool with one optional parameter and strong annotations, the description is nearly complete. It could briefly mention the optional type filter or expected return, but the schema covers the filter and the tool's simplicity reduces the risk of mis-invocation.

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%, so the single optional parameter is already fully documented. The description adds no further parameter-level meaning, which is acceptable because the schema carries the semantic burden.

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 uses a specific verb ('List') and a clear resource ('labels'), and explains that labels are used for tagging posts and media. This differentiates the tool from siblings like create_label, update_label, and delete_label by focusing on the read-only listing behavior.

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 phrase 'Use this when the user wants their post labels/tags' gives clear intent-based guidance for selecting the tool. It does not explicitly mention alternatives or exclusions, but the context is strong enough for an agent to know when this tool applies.

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