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

Annotations already declare readOnlyHint and openWorldHint, so the safety profile is covered. The description adds a genuine behavioral trait beyond the annotations: a fallback to searching around the id in user mode. That is useful, but it is terse and does not explain what the fallback returns or when it triggers.

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 with no wasted words; the purpose leads and the fallback qualifier follows. It is efficient, though the parenthetical caveat is dense and slightly cryptic.

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 read-only lookup with full schema coverage and no output schema, the description is adequate: it states the lookup and the fallback. It omits how the fallback result is shaped and gives no routing against near-duplicate siblings, leaving minor gaps.

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%, so channelId, messageId and the format enum are already documented in the schema. The description adds no parameter syntax or format detail, so the 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?

States a specific verb (busca) and resource (mensagem) plus the lookup key (id), and the word 'especifica' contrasts with the plural list/search siblings. It does not, however, explicitly name read_messages or search_messages as the alternatives, so differentiation is implied rather than stated.

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 gives no when-to-use guidance or exclusions relative to read_messages (plural, channel scan) or search_messages. The agent must infer from 'pelo id' that this is the single-message-by-id path, which is weak routing guidance given several overlapping siblings.

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