Best exchange house

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

With no annotations, the description carries the full behavioral burden, and it delivers non-obvious disclosure: the meaning of 'best' flips with side — lowest sell price when buying, highest buy price when selling. This prevents an agent from incorrectly assuming 'best' always means the lowest price. It also scopes the result temporally ('right now'), though it doesn't explicitly confirm read-only behavior or describe the result 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?

Two sentences with zero redundancy. The purpose is front-loaded in the first sentence, and the clarifying side semantics follow immediately in the second. Every clause earns its place, and the key disambiguation is packed into minimal space.

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 2-parameter lookup tool with fully documented schema parameters, the description covers the essential decision rule and temporal scope. The main gap is the absence of an output schema and no hint about what the result contains (house name, rate, timestamp). Given the tool's simplicity, this is close to complete but not fully so.

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%, so both parameters are already documented, earning the baseline 3. The description adds genuine value beyond the schema by coupling each side value to its ranking rule (buy → lowest sell price; sell → highest buy price), which is the tool's core logic. Currency adds nothing beyond the schema's ISO note, but the side explanation justifies a 4.

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 purpose: return the single best exchange house for buying or selling a currency, with 'right now' scoping it to current market conditions. 'The single best' implicitly separates it from siblings like list_houses and get_rates, though it doesn't name them explicitly. It stops short of a 5 because differentiation from siblings is implied rather than stated.

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 usage context is implied: use this when you want the one best casa de cambio for a given currency and side, rather than all houses or plain rates. The description gives no explicit when-to-use vs. when-not-to-use guidance and names no alternatives such as list_houses or get_rates. This meets the 'implied usage' level but nothing more.

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