[dotnet-port-api] Add agent-as-tool argument name/description customization

[PratikDhanave (PratikDhanave)]

Partial implementation of #1139.

agenttool hardcoded a single query string argument with a fixed description. Add ArgName and ArgDescription config options so a caller can rename/re-describe the argument the model sees — mirroring the .NET/Python as-tool argument options.

Change

• Config.ArgName (default "query") and Config.ArgDescription (default "input query to invoke the agent").
• Schema() emits the configured argument name/description; Call() reads the configured key (decoding into a map rather than a fixed struct field).
• Defaults are unchanged, so existing behavior and tests are unaffected.

Scoped to the argument customization; session propagation (the other half of #1139) is left for the design discussion there, since obtaining the caller session at Call time needs a mechanism the tool interface does not currently expose.

Test

• TestNew_CustomArgNameAndDescription: a custom ArgName:"task" is reflected in the schema (and the default query is gone), and Call with {"task":...} forwards the value to the agent. Fails to build before the change (fields absent), passes after.

[Copilot]

Copilot review overview

🟡 Changes recommended

Invalid non-string argument values are silently converted into blank queries instead of returning decoding errors.

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Review effort: Lite
Findings: 1

Open (1)

• Preserve string type validation for configured tool arguments · New

What changed in this PR

Adds configurable argument names and descriptions to agenttool, preserving existing defaults.

Changes:

• Added ArgName and ArgDescription configuration.
• Updated schema generation and argument forwarding.
• Added custom-argument tests.

File	Description
tool/​agenttool/​agenttool.go	Implements configurable argument metadata and invocation.
tool/​agenttool/​agenttool_test.go	Tests custom schema and argument forwarding.

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[Quim Muntal (qmuntal)]

https://github.com/microsoft/agent-framework-go/pull/1157/changes#r4068674786 needs fixings.

[github-actions]

API consistency review

Result	Scope
aligned	public API

Changed Go contract

• tool/agenttool.Config.ArgName (new, optional, default "query") and Config.ArgDescription (new, optional, default "input query to invoke the agent").
• functool.Schema() now emits the configured argument name/description instead of a hardcoded "query" property.
• functool.Call() decodes arguments into a map[string]json.RawMessage and reads the configured key, returning a JSON decoding error if that key is present with a non-string value (previously a fixed Query string struct field silently zero-valued on type mismatch).

Upstream evidence reviewed

Implementation	Source	Contract checked
.NET	dotnet/src/Microsoft.Agents.AI/AgentExtensions.cs#L69-L91	AsAIFunction hardcodes a single strongly-typed string query parameter (description "Input query to invoke the agent.") with no name/description override — this is the baseline Go previously matched for its default "query" arg name/description.
Python	python/packages/core/agent_framework/_agents.py#L657-L729	`Agent.as_tool(..., arg_name: str = "task", arg_description: str
Repo issue	microsoft/agent-framework-go#1139	Issue filed by the same author explicitly scopes this PR to argument customization only, deferring session propagation (the other parity gap) to future work, and confirms the existing "query" default was already intentionally aligned with .NET.

Assessment

This is a scoped, additive parity fix explicitly tracked by #1139. Go's new ArgName/ArgDescription options mirror Python's as_tool(arg_name=..., arg_description=...) precedent while preserving the pre-existing "query" default that matches .NET's hardcoded AsAIFunction parameter, so neither existing behavior nor defaults change for callers who don't set the new fields. The stricter Call() behavior — rejecting a wrong-typed value for the configured key instead of silently defaulting to an empty query — is consistent with .NET's strongly-typed string query parameter binding (a type mismatch there also fails before invocation), and is a reasonable, non-breaking tightening given the schema declares the argument as "type": "string". Session propagation remains intentionally out of scope per the linked issue and is not required for this PR to be complete. No actionable parity issues found.

Generated by Go API Consistency Review Agent · copilot · auto · 69.5 AIC · ⌖ 8.62 AIC · ⊞ 13.9K · ◷

[Copilot]

🟡 Changes recommended

Exact map lookup introduces an undocumented case-sensitivity compatibility regression.

3 open findings

• Preserve case-insensitive JSON key matching in default decoding · New
• Preserve string type validation for configured tool arguments
• Remove cross-language porting history from Go API documentation · New

🧠 Review effort: Balanced

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