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

Annotations already declare readOnlyHint and openWorldHint, but the description adds genuinely non-obvious behavior: cost ($0.002 USDC per successful call), the payment rail (x402 on Base/Solana/Arc), and that failed calls are not charged — critical for a paid endpoint. It also discloses result ordering ('newest start first'). The enumerated return fields partly duplicate the output schema and it says nothing about rate limits or result freshness, so not a 5.

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?

Front-loaded with the data source and scope, then filtering, then pricing — a sensible ordering with no filler sentences. Slight redundancy in listing every returned field when an output schema exists, but the text stays dense and earns most of its length.

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?

With an output schema present, the description doesn't need to enumerate return fields, and it supplies the data source, filter options, sort order, and full pricing/charging policy for a paid endpoint. Only pagination behavior beyond the schema's `limit` and any data-freshness caveat are left unaddressed.

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 100% and all three parameters are already documented with examples and defaults, so the baseline is 3. The description's only marginal addition is the sort order ('newest start first') and the framing of q as title words, which the schema already covers.

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 a specific resource (ADB financing — loans, grants, technical assistance) and its provenance (official IATI data via d-portal.org), so an agent knows exactly what dataset it gets. It lacks an explicit verb and never distinguishes itself from the many other finance-data siblings (e.g. finance_world_bank), so it falls short of a 5.

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?

States the available filters ('Filter by country (ISO2) and title words') and a practical precondition ('Open data, no key'), which implies when the tool is usable. It gives no when-to-use/when-not-to-use guidance and never names an alternative dataset or sibling to prefer, so usage must be inferred.

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