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

Annotations already cover the read-only, non-destructive profile, and the description adds real operational context: URL imports drop sideboards and Moxfield companions, provider access can fail, nothing is purchased or saved publicly, and bracket output is guidance rather than certification. It also enumerates the return payload including the TCGplayer cartUrl, so the agent knows what comes back without an output schema.

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?

Front-loaded with purpose, then proceeds through inputs, failure modes, outputs, and safety constraints in a logical order with no filler sentences. It is a single dense block without structure, which makes it slightly harder to scan for the parameter-level facts.

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 10-parameter tool with no output schema, the description covers return shape, safety guarantees, URL import caveats, and the owned/locked/excluded semantics that an agent needs to call it correctly. The remaining gap is the unstated role of maxChanges and bracket as tunable constraints.

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?

With only 30% schema coverage the description must compensate, and it does explain deck, owned (150 entries, 100 copies per card), locked/excluded (newline-separated names), budget in USD, and replaceCard's restriction behavior. However, maxChanges is never mentioned and bracket is only obliquely touched via the certification disclaimer, leaving two meaningful tuning parameters undocumented in both places.

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 and resource — finding lower-cost replacements for a decklist via budgetswap — which is clearly distinct from build_mana_base, search_cards, or upgrade_precon. It never names a sibling to route against, but the 'lower-cost' framing makes the intent unmistakable.

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?

Gives concrete input requirements (full quantity-prefixed list including commander, or a public Moxfield/Archidekt URL) and a fallback path when provider access fails. It also sets an operator expectation — show all warnings and let the player choose swaps — but does not explicitly say when to prefer find_replacements or upgrade_precon instead.

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