listar_fontes

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

With no annotations, the description carries the burden and does so well: it declares that sources with an open circuit respond "unavailable", that a count of 0 means an empty acervo, that the recorte describes the installed collection rather than the official source, and that three fields are experimental. It omits anything about cost, latency, or read-only guarantees, which are only implied by "lista".

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 purpose and the "start here" directive, then a compact per-field breakdown. It is on the long side and partly restates return fields that an output schema already exposes, but each clause (circuit states, experimental fields, recorte limits) adds genuine interpretation rather than filler.

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 zero-parameter discovery tool with an output schema, the description covers what an agent needs: the shape of the response, the meaning of empty counts, and the two degraded states (nao_confirmado_no_acervo, unavailable). Nothing required to call it correctly 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?

The tool takes zero parameters, so the baseline is 4. The description spends its space on return-value semantics instead, which is the right allocation for a no-arg tool.

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?

States a specific verb and resource ("Lista as fontes") plus the scope it covers (what each source covers and the instalado acervo recorte), so an agent knows it is an inventory/discovery call rather than a search. It never names a sibling tool or explicitly contrasts itself with buscar_legislacao or pesquisar_jurisprudencia, so sibling differentiation is left implicit through the "Comece por aqui" framing.

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?

"Comece por aqui" gives a clear entry-point instruction, and the note that outside the recorte the answer becomes nao_confirmado_no_acervo or depends on a live query gives concrete downstream guidance. No explicit when-not-to-use or alternative-tool routing is stated.

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