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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering safety. The description adds valuable context by detailing the returned content (tipo, emissor, distribuidor, rentabilidade, prazo, vencimento, garantias, riscos), which is not present in annotations. No contradictions.

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 efficient: two main sentences plus a keyword list. It front-loads the core purpose, then usage, then helpful English keywords. No wasted words, and the structure is clean.

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?

Despite no output schema, the description enumerates the types of details returned, giving the agent a clear picture of the tool's output. Combined with usage guidance and sibling references, it is complete for a simple read-only detail tool with two optional parameters.

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%, with both id and slug already described. The description adds a slight clarification that either 'ID ou slug' can be used for lookup, but this is marginal and not fully explicit about exclusivity. Baseline 3 is appropriate given the schema handles the heavy lifting.

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 returns complete details of a specific investment by ID or slug, listing the types of information included. It distinguishes itself from sibling get_best_investments by mentioning it deepens an item from that list.

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 provides explicit context for when to use the tool: 'Use quando o usuário quiser entender melhor uma oportunidade específica... ou aprofundar um item retornado por get_best_investments.' It references an alternative tool by name, but does not explicitly state exclusions or when not to use it.

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