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

Annotations already establish the safe-read profile (readOnly, idempotent, non-destructive, closed-world). The description adds genuine non-obvious behavior: per-band official/interpreted/approximate status, provenance/verification dates, rounding rule, and the TAG exclusion. Pagination/rate limits are irrelevant for a static reference lookup, so this is close to sufficient.

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?

Four tightly packed fragments, front-loaded with the lookup purpose and ending with the key caveat. Dense but essentially waste-free; the return-value enumeration could be trimmed slightly given an output schema exists.

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 two-optional-parameter static reference tool with an output schema, the description covers purpose, usage, caveats, exclusions and result semantics. Nothing an agent needs to invoke it correctly is missing.

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%, so the description must carry the burden, and it does: it names the four houses and front/back and the word 'optionally' signals both filters are non-required. It adds little about how combined filtering behaves, keeping it below a 5.

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 (look up) and resource (card centering thresholds) with the exact scope (PSA, BGS, CGC, SGC, optional house/front-back). The closing line 'centering ceilings, not grade predictions' explicitly separates it from grade_centering, so an agent can pick it apart from its siblings without reading their schemas.

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?

'Use for threshold/rules questions and source checks' gives clear selection context, and the TAG exclusion narrows applicability. It stops short of naming the sibling tools or stating when-not to use it, but the domain is unambiguous.

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