explain_decision

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

With no annotations, the description carries the burden of disclosing behavior. It clearly states that it walks the causal-parent chain to the root and returns the chain in order. It omits edge cases (e.g., missing root, cycles) and performance characteristics, but for a read-only traversal tool the core behavior is well explained.

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?

The description is two sentences, front-loaded with the core action and result, followed by practical usage examples. Every sentence adds value 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?

Given no output schema, the description adequately describes the return value ('chain in order from requested event to its root') and gives a concrete walk-through example. It does not detail the shape of each chain element, which would improve completeness, but it is sufficient for a straightforward traversal 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 schema covers 'max_depth' with a description and default, but 'event_id' has no schema-level description. The description adds conceptual meaning ('the requested event', causal-parent chain) but does not specify the format or expected identifier style for event_id. Schema coverage is 50%, and the description only partially compensates.

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 clearly identifies a specific verb ('Walk an event's causal-parent chain back toward the root') and resource ('event's causal-parent chain'), and explains the output ordering. It does not explicitly contrast with the sibling tool 'explain_event', leaving some ambiguity about when to choose one over the other.

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 provides concrete use cases ('why did this fill happen', 'trace the cause of order 42') and explains what the chain reveals. However, it offers no explicit when-not-to-use guidance or alternatives, so it stops short of a full 5.

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