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

Annotations already cover readOnly/idempotent/non-destructive, and the description adds substantive behavior beyond them: it is a stub, the live lookup is disabled, an Attic API key is required, and without a key it falls back to explaining Attic Beyond. It also warns against fabricating results, which is exactly the failure mode an agent needs flagged.

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?

Five short sentences, each carrying a distinct constraint, with the STUB warning front-loaded. No redundant padding, and the most decision-critical fact (stub / no grade) comes first.

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?

With no output schema, the description must carry return semantics; it clearly states what is NOT returned but never specifies what a successful call yields beyond the API-key fallback. For a stub tool this is nearly complete, but the positive return shape remains unstated.

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?

One required parameter with 100% schema coverage; the schema already explains that 'cert' is a PSA certification number and that the live lookup is not enabled. The description adds nothing new about the parameter itself, so baseline 3 applies.

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 outright that this is a stub lookup for a PSA cert and immediately delimits scope by denying it returns a grade or population and that PCGS comps are not offered. That differentiates it from siblings like attic_card_sold_comps, though the positive purpose (what it does return, e.g. a Beyond explanation) is only implied.

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?

It gives explicit when-not-to-use guidance: 'Do not call this to answer what a card graded or sold for,' plus the PCGS exclusion. It stops short of naming the correct sibling tool to use instead, 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.