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

Adds context annotations cannot express: every call is billed in USDC from a configured wallet, charges are gated by per-call/session/daily budget caps, and results are explicitly flagged as third-party data rather than instructions (a prompt-injection warning). Annotations only say readOnlyHint=false and openWorldHint=true, so this is meaningful added value.

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?

Pricing and the free_sample escape hatch are correctly front-loaded, and the bulleted product list is scannable. But the description is cut off mid-sentence in both product entries, leaving dangling text that wastes space and destroys information.

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?

Payment, budget behavior, and the injection caveat are well covered, and the absence of an output schema is partly mitigated by pointing to free_sample for a real sample answer. Still, the truncated product list leaves the parameter contract incomplete for a tool with a free-form nested params object.

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 baseline is 3, but the nested `params` object is additionalProperties:true and the description is the only place product-specific parameter names (pair*, currency, id*, seriesId) appear. Unfortunately the text is truncated mid-entry ('e.g.' and 'Federal Reserve Bank of St.'), so the enum-to-parameter mapping is only partially usable.

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?

Names the specific resource families (FRED economic time series and ECB euro reference FX rates) and enumerates the two product ids with prices. Clear enough to separate it from generic siblings like market_quote or open_data_search, though it never explicitly contrasts itself with them.

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?

Gives one concrete routing rule — use free_sample before paying — plus the budget-cap caveat via confirm_over_cap. However it offers no guidance on when to pick macro.fred.series over macro.ecb.fx, nor how this differs from call_product/list_products/get_price_quote in the same family.

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