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

Annotations already declare readOnly, idempotent, non-destructive and closed-world, so safety is covered. The description adds real value beyond them by disclosing what comes back (source links, review date, limitations), which explains the guide's trust profile and recency characteristics.

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, zero filler. The positive capability is front-loaded and the exclusion clause follows immediately where an agent's decision ambiguity would sit.

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?

No output schema exists, but the description compensates by naming the return contents and their caveats, and the annotations cover the safety profile. Adequate for a 2-parameter read tool, though it says nothing about guide length, depth or language coverage per brand.

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 50%: the language parameter is documented in-schema, but the brand enum carries no per-value description. The description only states there are eight brands, which the enum already establishes, so it adds no meaning about brand-specific content differences. Baseline 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?

Specific verb (Read) plus resource (published guide) and scope (one of eight collectible brands), with the payload spelled out: official source links, review date, limitations. The final exclusion sentence separates it from sibling tools like labubu_fake_signals and labubu_rarity_odds without needing to open a schema.

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?

Explicitly states when NOT to use it (current stock, resale valuation, authentication), which rules out the closest sibling intents. It stops short of naming the correct alternative tool for those cases, so routing is implied rather than prescribed.

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