Get System Marginal Prices

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

Annotations already declare readOnlyHint and idempotentHint, so the safety profile is covered. The description adds meaningful behavioral context: timezone handling ('America/Edmonton'), interval boundary semantics, and the 7-day range limit. It does not discuss pagination or response size, but the output schema and limit/offset parameters cover that. This is a solid addition beyond 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?

Two sentences with no fluff. The core functionality is front-loaded, followed by the routing alternative and key constraints. Every sentence earns its place.

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?

The description covers all essential calling context: units, timezone, interval semantics, range limit, and the alternative tool. The output schema exists, so return values are documented. An agent has everything needed to correctly invoke this tool without further research.

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 high (start/end have descriptions with timezone and inclusivity). The description adds value by specifying units ('CAD/MWh'), 'minute-level' resolution, and the 'Maximum range: 7 days' constraint, which are not in the schema descriptions. It also clarifies the inclusive/exclusive interval pattern. This goes beyond the schema's structured info.

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 ('Returns'), resource ('AESO System Marginal Price (SMP) observations'), units ('CAD/MWh'), and interval semantics ('minute-level ... [start, end)'). It also explicitly differentiates from the sibling get_pool_prices, making the distinction clear without opening 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?

Provides an explicit when-not-to-use instruction by directing users to get_pool_prices for hourly settlement prices, and sets a concrete constraint (maximum range 7 days). This gives an agent clear decision criteria for selection.

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