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

Annotations already declare readOnlyHint=true and destructiveHint=false, covering the safety profile. The description adds that the tool reports link state and next actions rather than performing a fix, but it does not describe possible link states, return specifics, or any operational caveats. This is adequate but not rich.

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?

Two short sentences with no filler. The core purpose and the when-to-use instruction are both front-loaded, and nothing repeats the annotations or schema.

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 read-only diagnostic tool, the description supplies the essential trigger ('when a Zalo tool errors') and the expected content ('link state' and 'what to do next'). There is no output schema, but enumerating exact states is not necessary for the agent to invoke it correctly.

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 input schema has zero parameters and 100% schema coverage, so there is no parameter burden for the description to carry. Under the zero-parameter baseline, the description appropriately says nothing about parameters.

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 ('Reports'), a clear resource ('Zalo's link state'), and an actionable outcome ('what to do next'). It also explicitly ties the tool to error situations, which distinguishes it from Zalo tools like zalo_connect or zalo_send_message.

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?

Provides an explicit usage trigger: 'Call it first when a Zalo tool errors.' This gives clear precedence and context. It does not name alternative diagnostic tools or spell out when not to use it, which keeps it just short of a 5.

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