explain_decision

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

No annotations provided, so description carries full burden. It discloses the tool walks parent chains, returns ordered chain, and respects max_depth. It implies read-only behavior (no destructive hints). The behavior is transparent with no contradictions.

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: first states action, second provides usage context. No wasted words, information is front-loaded. Every sentence serves a purpose.

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?

No output schema, so description must explain return value. It says 'Returns the chain' and hints at content (signal, event) but lacks specifics on structure (e.g., list of objects, fields). For a tool with 2 params and no nesting, this is adequate but incomplete.

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 coverage is 50% (max_depth has description, event_id does not). The description does not add explicit parameter documentation, but indirectly clarifies event_id as 'the requested event'. This adds minor value beyond the schema. For a required string parameter, more explicit format guidance would help.

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 uses a specific verb ('walk') and resource ('event's causal-parent chain') and clearly states it returns the chain in order. It distinguishes itself from siblings like 'explain_event' by focusing on causal parent chain tracing vs. general event explanation.

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 explicitly tells when to use: when the user asks 'why did this fill happen' or 'trace the cause of order 42'. It gives concrete examples of questions it answers. It does not explicitly state when not to use, but the context is clear enough.

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