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

Annotations already declare readOnlyHint=true, and the description adds value by disclosing the exact return payload (archetype, why it works, limitations, full list with copy counts) and the special Trainer-target behavior with an 'explicit effect-data limitation.' No contradiction with annotations.

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?

Three short sentences front-load the core purpose, then add output expectations and the one input caveat. Every sentence earns its place and there is no repetition of schema metadata.

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 fully covers return values (archetype, rationale, limitations, full card list with counts) and the edge case of Trainer cards. Combined with 100% schema coverage and readOnlyHint annotation, the agent has enough to invoke the tool correctly.

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 100%, so the baseline is 3. The description adds meaningful semantics by stating that query and cardId are alternatives ('either ... or'), clarifying how the agent should populate them; it also explains the practical effect of choosing a Trainer target, which the schema alone does not convey.

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 opens with a specific verb and resource: 'Build a complete, legal 20-card Pokémon TCG Pocket deck around a chosen card.' It enumerates concrete outputs (archetype, rationale, limitations, card list with counts) and distinguishes itself from siblings like evaluate_deck and simulate_matchup by focusing on deck construction around a desired card.

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 clearly states the invocation context ('around a chosen card') and gives input guidance ('Give either a card name to search for or a gameplay card id'). It does not explicitly name alternatives or when-not-to-use conditions, but the 'chosen card' framing is clear enough to route an agent away from evaluation/simulation siblings.

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