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

Annotations already declare readOnlyHint=true and openWorldHint=false, so the safety profile is covered. The description adds meaningful context beyond them by stating it does not consult case progress, telling the agent the result is derived purely from the number rather than fetched state.

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?

A single front-loaded sentence states the validate-and-explain behavior with the scope-limiting clause positioned to prevent misuse. Every element earns its place with no redundancy.

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?

An output schema exists, so return values need not be described, and the description covers inputs, behavior, and the non-consultation scope. It is essentially complete for a single-parameter decoder, with only the explicit sibling routing omitted.

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 single parameter's CNJ format is fully documented in the schema. The description mentions the decoded parts but adds no format or syntax detail for the input beyond what the schema already provides, so the baseline of 3 applies.

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?

Names a specific verb-and-resource pair (validates a CNJ process number and explains its parts) and enumerates exactly what is decoded (year, segment, court, origin). The closing clause 'sem consultar o andamento' cleanly carves it away from the sibling consultar_processo.

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 phrase 'sem consultar o andamento' gives a clear usage boundary against the consultar_processo sibling, implying this tool is for structural decoding only. It stops short of naming the alternative tool explicitly or stating a positive 'use this when' trigger, so it is clear context rather than full when/when-not routing.

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