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

Beyond the annotations (readOnly, idempotent, non-destructive), the description discloses meaningful behavior: raw content is returned according to mime-type, metadata is included, and nonexistent URIs yield `_erro` instead of an exception. This error-handling detail is especially valuable and goes beyond what annotations alone convey.

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 tightly structured: a one-sentence purpose, a brief note on return behavior, an illustrative JSON block, and the error case. Every sentence earns its place, and the key purpose is front-loaded. The format is easy to scan and parse.

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?

For a single-parameter tool with a rich schema, clear annotations, and an output schema, the description covers everything needed to call it correctly: purpose, return shape, mime-type behavior, and error semantics. The only remaining context—discovering URIs—is already handled by the parameter schema. Nothing essential is missing.

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%, and the schema's parameter description already explains how to discover and format URIs with concrete examples. The tool description itself does not add further parameter-level detail, which is acceptable given the schema's richness. Baseline 3 is appropriate because the description does not need to compensate for schema gaps.

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 opens with a specific verb and resource: 'Lê o conteúdo de um MCP Resource pela URI.' This clearly distinguishes it from sibling tools that list resources or fetch prompts. It also states what is returned (raw content and metadata), leaving no ambiguity about the tool's role.

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 makes the tool's context clear—reading a resource by URI—but does not explicitly contrast it with alternatives in the description itself. However, the parameter schema provides direct guidance: 'Use `compras_listar_resources` para descobrir URIs disponíveis,' which tells the agent how to discover valid URIs. This is clear context with a practical prerequisite, though not a full when/when-not comparison.

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