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

Annotations already declare read-only/idempotent behavior, and the description adds meaningful behavior beyond them: it specifies the return shape (nome, texto, argumentos_usados), that texto is the PromptMessage[0] content, and that missing prompts or required arguments yield an _erro diagnostic instead of an exception. This gives the agent a clear expectation of both success and failure behavior.

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 compact, front-loaded with the core purpose, and every block earns its place: purpose, intended use, return contract, and error behavior. The JSON sample is minimal and illustrative.

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 2-parameter, read-only render tool, the description is complete: it explains why the tool exists, what the output means, how errors are reported, and the schema/annotations cover the remaining parameter and safety details.

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 the schema already gives rich semantics for both parameters, including examples and how to discover prompt names. The description itself adds little beyond noting that missing required arguments are handled, so a baseline 3 is appropriate.

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 opening sentence uses a specific verb-resource pair ('Renderiza um MCP Prompt') and states the concrete outcome: returns ready-to-use text. The follow-up clarifies it returns the content of PromptMessage[0] as a script for executing other tools, which clearly separates it from the listing sibling com compras_listar_prompts.

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 explains when the tool fits: get a rendered prompt that guides the LLM through a flow using this server's tools before the LLM calls other tools. It provides clear context, though it does not explicitly state exclusions or name compras_listar_prompts as the prerequisite discovery step (that lives in the parameter schema).

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