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

Annotations already declare destructiveHint=true and readOnlyHint=false, and "create or update" is consistent with an overwrite rather than contradicting them. The description adds genuine value with the quota limits and the negative scope note about not fetching live listings. It still omits what happens to an existing alert's settings on update and whether the operation can fail on quota exhaustion.

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-loaded with the action and free of filler. Each sentence carries a distinct fact: action, quota, and scope negation. It is efficient, though the quota sentence is compressed to the point of being terse.

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?

This is a mutating tool flagged destructive with zero parameter documentation and no output schema, so the description should explain update semantics and return behavior. It does not say what the agent gets back, whether an existing alert is overwritten or merged, or how quota failures surface. Only the scope and quota limits are covered.

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 description coverage is 0% across all three parameters, so the description must carry the burden and does not: cardId, language, and targetPriceEur are never mentioned. The ambiguous field is "language" — nothing indicates whether it scopes the alert to a card language or configures notification language. Only targetPriceEur is self-explanatory from its name.

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?

"Create or update a price alert" states a specific verb pair and resource, which clearly separates it from price_alert_delete and list_alerts in the sibling list. The added clause "Does not fetch live listings" further bounds the operation. It stops short of naming a sibling directly, but the resource is unambiguous.

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?

The tier quotas (Free: 10, Premium: 100) give useful context about when the call will succeed, and "create or update" implies an upsert. However, there is no explicit guidance on when to use this versus list_alerts or price_alert_delete, and no statement of prerequisites such as needing the card to already exist.

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