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

Annotations already declare readOnlyHint=true, idempotentHint=true, destructiveHint=false and openWorldHint=false, so the safety profile is covered without the description. The description adds only the meaningful nuance that this is partner-scoped (listing across all instances under a partner account) rather than single-instance scoped; it says nothing about result size, pagination, or failure modes for an invalid token.

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?

One front-loaded sentence with no filler, and the key scope qualifier ('partner instances') appears immediately. It is efficient but so terse that it omits any operational detail rather than being optimally informative.

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 one-parameter, read-only list operation with full schema coverage and complete annotations, no output schema is needed and the description covers the essential scope distinction. A mention of whether results are paginated or what an instance record contains would close the remaining gap.

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?

There is a single parameter with 100% schema description coverage ('Partner Token from your GREEN-API dashboard'), so the schema already carries the semantics. The description adds no format, scope, or permission detail beyond what the schema states, making the baseline 3 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 and resource ('List all partner instances') and names the API surface ('GREEN-API Partner API'), which separates it from instance-scoped siblings like whatsapp_get_state or whatsapp_create_instance. It does not explicitly name a sibling it is not, so it stops short of a 5.

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?

There is no guidance on when to call this versus the many other instance-related tools (create_instance, delete_instance, get_state), no prerequisites beyond the implied partner token, and no exclusions. The agent must infer usage from the name alone.

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