Get System Marginal Prices

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

Annotations already declare read-only, idempotent, and non-destructive behavior, so the description adds context beyond that: interval boundaries ([start, end)), timezone (America/Edmonton), and maximum range. This provides practical behavioral expectations not covered by annotations, though it stops short of describing error conditions or output shape.

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 concise sentences, front-loaded with the core purpose, followed by usage guidance and constraints. No redundant wording; every sentence adds value.

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?

Given the tool has an output schema and safety annotations, the description covers essential decision-making information: frequency, units, interval semantics, timezone, range limit, and the key alternative. It is sufficiently complete for an agent to select and invoke 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%: both start and end are fully described with types, formats, and timezone interpretation. The description reinforces interval semantics but adds no new parameter-level detail beyond what the schema already provides, so the baseline of 3 is appropriate.

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 clearly states the action ('Returns') and the specific resource ('AESO System Marginal Price (SMP) observations'), with units and interval semantics. It differentiates from the sibling tool get_pool_prices by specifying minute-level frequency, making the purpose 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?

Explicitly directs users to prefer get_pool_prices for hourly settlement prices, giving a clear alternative. Also provides a maximum range constraint (7 days) and timezone note, helping the agent decide when this tool is appropriate.

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