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

Annotations already declare destructiveHint=true and idempotentHint=true; the description adds real context beyond that: the requirement to leave at least one setting, the pwk_live_ key source, and a full structured error contract (error.code, http_status, retry_recommended, retry_after_seconds). It stops short of stating that omitted fields are left unchanged or what clearing a threshold does.

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 sentences, front-loaded with purpose and the mutable-field list, followed by the constraint, auth, and error contract. It is tight overall, though enumerating every error field name is slightly verbose compared to what the output schema already provides.

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 mutation tool with destructive annotations and an output schema, the description covers auth, key constraints, and error behavior well. The main remaining gap is partial-update semantics (whether unspecified fields are preserved), which an agent would still need to infer.

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 60% schema coverage across 10 parameters, the schema already documents api_key, alert_id, and the null-to-clear threshold behavior. The description reinforces only the threshold-free notify_on_drop/notify_on_rise semantics and is_active; it says nothing about name, webhook_url, or notify_email, so it adds partial value but does not fully compensate for the coverage gap.

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 a specific verb and resource ("Update a price alert") and enumerates the mutable fields: threshold-free notify_on_drop/notify_on_rise, thresholds, and is_active. This clearly separates it from create_price_alert, delete_price_alert, and get_price_alert even without naming them, though no sibling is referenced explicitly.

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?

Usage is only implied: the agent can infer this is the tool for modifying an existing alert, and the constraint "At least one setting must remain" plus the API-key prerequisite are useful guardrails. However, there is no explicit when-to-use versus get_price_alert or delete_price_alert, and no guidance on partial-update expectations.

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