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

Annotations already declare readOnlyHint=true, idempotentHint=true, and destructiveHint=false. The description adds valuable behavioral detail beyond these: 'Malformed chains fail closed and never claim a current Decision,' which informs error handling. This is a meaningful addition without contradicting annotations.

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 sentences with zero waste. The first sentence gives purpose and ordering, the second gives a critical behavior. Information density is high and front-loaded.

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?

The tool has an output schema (though not shown here), so return value details are covered. The description explains the ordering and failure behavior, which are the key contextual elements. The term 'visible' is slightly ambiguous but not critical; overall it is complete for a read-only retrieval tool.

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 100% coverage—the parameter description ('Decision identifier from any point in the chain') is already specific. The tool description adds no additional parameter semantics, so it contributes zero beyond the schema. The baseline of 3 applies since the schema does the heavy lifting.

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?

The description states a specific verb ('Retrieve') and a precise resource ('complete visible Decision supersession chain') with additional ordering context. It clearly distinguishes from siblings like decision_log_get_decision (single) and decision_log_get_current_decision (current only) by emphasizing the full chain.

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 conveys clear context: it is for retrieving the entire supersession chain in chronological order. While it doesn't explicitly name alternatives or conditions to avoid, the purpose is unambiguous and an agent can infer when to use it. Lacks explicit exclusion criteria but provides enough context.

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