fix: handle missing 'type' field in tool parameter properties for OpenAITokenCounter

[octo-patch]

Fixes #1397

Problem

When PlanNotebook is enabled, some plan-related tools (e.g., view_historical_plans) define parameter properties that do not include a type field. The _calculate_tokens_for_tools function in _openai_token_counter.py attempts to access properties[key]["type"] directly, causing a KeyError when the field is absent.

Solution

Replace the direct key access properties[key]["type"] with properties[key].get("type", "") so that missing type fields are handled gracefully with an empty string fallback, which is safe to encode and contributes 0 extra tokens.

Testing

Manually verified: constructing a tool schema where a property omits the type field (as in the view_historical_plans plan tool) no longer raises a KeyError when token counting is invoked.

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