The top-level delegate_task description repeated content the model already
receives through parameter descriptions: the concurrency limit (tasks param),
the full nesting clause (role param), context-passing guidance (goal/context
params), and background semantics (background param). Every API call paid for
the duplication (~4,000 chars).
The description now carries only what exists nowhere else in the schema:
use/don't-use routing (execute_code, cronjob), the no-poll rule, the
non-durability warning, the self-report verification contract with concrete
verbs, the language-passing example, the leaf blocked-tool list, and model
inheritance. 3,963 -> 1,704 chars (~570 tokens saved per API call), and the
top-level text is now static (dynamic limits flow only through the two param
descriptions, which are already rebuilt per get_definitions() call).
A/B benchmark across 4 models (gpt-4o, gpt-4o-mini, claude-haiku-4.5,
llama-3.3-70b) showed the naive compaction in PR #72813 regressed weaker
models on exactly the passages it cut (side-effect verification 8/8->0/8 on
gpt-4o-mini; language passing 3/3->0/3 on haiku-4.5). This version keeps
those benchmark-sensitive hooks verbatim.
Tests pin the contracts at keyword level (not prose-literal) plus a size
ceiling, and verify dynamic limits still reach the model via the tasks/role
param descriptions.
Refs #72737, supersedes the delegate_task half of PR #72813.
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