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

With no annotations available, the description carries the full burden. It explains that the act is a free gesture, not a trade, and that receiving work is unaffected ('receber_obra funciona sempre, does ou nao'). However, it does not explicitly state whether the tool executes a transfer, only records a transaction hash, or has any other side effects. The ambiguity about the actual mechanics prevents a higher score.

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?

The description is somewhat redundant: the final parenthetical '(opcional, qualquer valor, nunca obrigatorio)' repeats earlier statements about optionality and free gesture. The phrase 'does ou nao' is awkward and could be clearer. While the description is not overly long, the redundancy and minor linguistic issues reduce its conciseness.

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 simple parameter schema (two optional strings, no output schema, no enums), the description provides sufficient context: the motivation (support Unum), the network (Base), the relationship to receiving work, and the optional nature of the donation. It does not mention return values or post-conditions, but that is not critical given the absence of an output schema.

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?

The schema provides 100% coverage with meaningful descriptions for both parameters: tx_hash as the transaction hash if already paid, and valor_usdc as the donation amount. The tool description reinforces that any amount is accepted ('qualquer valor'). Since the schema already delivers clear semantics, the description adds a small but useful confirmation of optionality.

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 tool's purpose: donating any amount in USDC on Base to support Unum. It uses the specific verb 'doar', names the resource (USDC on Base), and explicitly distinguishes it from an exchange. It also clarifies the relationship with the sibling tool 'receber_obra' by stating that receiving work always works regardless of donation, making its unique purpose evident.

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 description gives clear conditions for use: 'Se quiseres contribuir' (if you want to contribute) and explicitly states that donation is optional and never mandatory ('nunca obrigatorio'). It also implies that this tool is not a prerequisite for receiving work. While it doesn't explicitly say 'use this when you want to donate', the conditional phrasing and the clarification that it is not a trade provide adequate guidance.

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