fix: add placeholder for MCP tool return type field

[sharindanic]

Purpose

Fixes wso2/product-integrator#731

The return type field in the MCP tool form was displaying undefined as placeholder text when a user adds a new
tool in the MCP service creator.

Goals

Show a meaningful placeholder for the return type field instead of undefined.

Approach

Added a placeholder property to the returnType field in McpToolForm/index.tsx that falls back to "e.g. string,
int, json" when no placeholder is defined in the metadata.

UI Component Development

N/A - No new UI components added

Manage Icons

N/A - No new icons added

User stories

N/A

Release note

Fixed undefined placeholder text in MCP tool return type field.

Documentation

N/A - Minor placeholder fix, no doc impact

Training

N/A

Certification

N/A

Marketing

N/A

Automation tests

N/A

Security checks

• Followed secure coding standards? yes
• Ran FindSecurityBugs plugin? N/A
• No keys or secrets committed? yes

Samples

N/A

Related PRs

N/A

Migrations

N/A

Test environment

N/A

Learning

N/A

Summary by CodeRabbit

• Improvements
  • The return type input now shows a contextual placeholder (falls back to an example like "e.g. string, int, json") to help users enter valid formats. The placeholder is driven by the form's underlying model so it reflects any available contextual guidance.

[CLAassistant]

All committers have signed the CLA.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 5182fd59-3dc7-4385-ae5b-d7233c9104c6

📥 Commits

Reviewing files that changed from the base of the PR and between 8c5e9d9 and 6a26ca2.

📒 Files selected for processing (1)

• workspaces/ballerina/ballerina-visualizer/src/views/BI/ServiceDesigner/Forms/McpToolForm/index.tsx

🚧 Files skipped from review as they are similar to previous changes (1)

• workspaces/ballerina/ballerina-visualizer/src/views/BI/ServiceDesigner/Forms/McpToolForm/index.tsx

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📝 Walkthrough

Walkthrough

The PR fixes the MCP tool form's return type placeholder by initializing it from model.returnType.placeholder, falling back to model.returnType.metadata?.placeholder, and finally to the literal "e.g. string, int, json" when prior values are missing.

Changes

Cohort / File(s)	Summary
MCP Tool Form Field workspaces/ballerina/ballerina-visualizer/src/views/BI/ServiceDesigner/Forms/McpToolForm/index.tsx	Set returnType FormField placeholder to resolve from model.returnType.placeholder, then model.returnType.metadata?.placeholder, and default to "e.g. string, int, json".

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Poem

🐰 I hopped through code both near and far,
Found a missing hint beneath a star,
I stitched a fallback, snug and sunny,
Now placeholders read clear and funny,
Hooray — no more "undefined" scar!

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 0.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: adding a placeholder for the MCP tool return type field.
Description check	✅ Passed	The description addresses all required template sections with appropriate content, though some sections are marked N/A as they don't apply to this minor fix.
Linked Issues check	✅ Passed	The code changes directly address the linked issue #731 by adding a meaningful placeholder to prevent 'undefined' from appearing in the return type field.
Out of Scope Changes check	✅ Passed	All changes are scoped to the returnType field placeholder configuration in McpToolForm; no unrelated modifications are present.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

---

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[coderabbitai]

Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Inline comments:
In
`@workspaces/ballerina/ballerina-visualizer/src/views/BI/ServiceDesigner/Forms/McpToolForm/index.tsx`:
- Line 204: The placeholder lookup is using
model.returnType.metadata?.placeholder (which isn't defined) instead of the
top-level PropertyModel.placeholder; update the expression in the component to
prefer model.returnType.placeholder first, then fall back to
model.returnType.metadata?.placeholder (or the hardcoded default), so configured
placeholders on PropertyModel are honored—look for the usage of model.returnType
in the component (the placeholder prop at line with placeholder:
model.returnType.metadata?.placeholder || ...) and change it to check
model.returnType.placeholder before the metadata fallback.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Pro

Run ID: 2304a30b-0d38-451e-97bd-7698bb24acd6

📥 Commits

Reviewing files that changed from the base of the PR and between db77727 and 8c5e9d9.

📒 Files selected for processing (1)

• workspaces/ballerina/ballerina-visualizer/src/views/BI/ServiceDesigner/Forms/McpToolForm/index.tsx