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

With no annotations, the description carries the full burden, and it does disclose a real behavioral trait: history is stored observations and may be sparse ('may not contain a point for every hour'). It says nothing about return shape, pagination, auth, or rate limits, so it only partly covers the burden.

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, front-loaded with purpose, second sentence delivering the caveat. No filler, nothing repeated from the title.

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?

No output schema and no annotations, so the description should say more about what a returned observation looks like and how the 'days'/'side' parameters shape results. It covers purpose and one data caveat, which is minimally viable for a simple read tool but leaves real gaps.

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 only 25% (only 'bank' is documented), but the description does add that the query is scoped to one bank and one currency. It says nothing about 'days' or 'side'; those parameters are still partly inferable from schema constraints (1-90 default 30) and the enum, which keeps this at a baseline 3 rather than lower.

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 ('Return'), a specific resource ('historical TT rates'), and the scoping dimensions ('one Thai bank and currency'). This separates it from siblings like get_best_thai_fx_rate and list_thai_fx_banks, though no sibling is named 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?

No statement of when to choose this over compare_thai_bank_rates or get_best_thai_fx_rate, and no prerequisites or exclusions. The only guidance is the data caveat about missing hourly points, which is a data-quality note rather than tool-selection guidance.

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