feat: respect CODEX_DEFAULT_MODEL env var in tool descriptions

[MrYoqaq]

Problem

When using this MCP server with AI agents (like Claude), the agent sees the hardcoded model list in tool descriptions:

Specify which model to use (defaults to gpt-5.3-codex). Options: gpt-5.3-codex, gpt-5.2-codex, ...

This causes issues because:

1. The model list becomes outdated as OpenAI releases new models
2. AI agents may try to use outdated model names from this list
3. Even with CODEX_DEFAULT_MODEL env var set, the description still shows the old list

Solution

When CODEX_DEFAULT_MODEL environment variable is set:

• Use the env var value as default model in tool descriptions
• Hide the hardcoded model list (which may become outdated)

This way, users who set CODEX_DEFAULT_MODEL get clean descriptions without outdated model names.

Changes

• Modified getModelDescription() in src/types.ts to read the env var
• Backward compatible: original behavior preserved when env var is not set

Summary by CodeRabbit

• Refactoring
  • Model selection descriptions now support environment-based configuration. When enabled, descriptions provide simplified guidance for model selection. When not configured, comprehensive model listings display as before, ensuring full backward compatibility with existing setups.

[coderabbitai]

Walkthrough

The getModelDescription function in src/types.ts has been enhanced to support environment-variable configuration. When CODEX_DEFAULT_MODEL_ENV_VAR is set, it returns simplified descriptions with the environmentally-determined default model; otherwise, it retains the original behavior with full model listings.

Changes

Cohort / File(s)	Summary
Environment-aware model description src/types.ts	Modified getModelDescription to conditionally check for CODEX_DEFAULT_MODEL_ENV_VAR; returns simplified prompts when the variable is set, otherwise provides original behavior with full AVAILABLE_CODEX_MODELS listing.

Possibly related PRs

• feat(model): update default model to codex 5.3 #110 — Directly builds on the same constants and getModelDescription function with environment-variable awareness changes
• Update default model to gpt-5.1-codex #70 — Related to how CODEX_DEFAULT_MODEL is determined and influences default model behavior
• feat(model): default to gpt-5.2-codex and update model docs/options #84 — Related to how default model selection and presentation is configured across tool descriptions

Poem

🐰 A model description now bends to the breeze,
Checking the winds (environment, please!),
Simplified paths when the variable's set,
Full lists when it's not—no regrets yet! 🌬️✨

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~8 minutes

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly and specifically summarizes the main change: respecting the CODEX_DEFAULT_MODEL environment variable in tool descriptions, which aligns perfectly with the core objective of the changeset.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Post copyable unit tests in a comment

Tip

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[coderabbitai]

🧹 Nitpick comments (1)

src/types.ts (1)

34-45: Centralize the default-model lookup.

This now duplicates the same process.env[CODEX_DEFAULT_MODEL_ENV_VAR] || DEFAULT_CODEX_MODEL policy that already exists in src/tools/handlers.ts for execution. Pulling that into a shared helper would reduce drift between what the tool advertises and what it actually runs.

♻️ Proposed refactor

+export const getConfiguredDefaultModel = () =>
+  process.env[CODEX_DEFAULT_MODEL_ENV_VAR] || DEFAULT_CODEX_MODEL;
+
 export const getModelDescription = (toolType: 'codex' | 'review') => {
-  const envModel = process.env[CODEX_DEFAULT_MODEL_ENV_VAR];
-  const defaultModel = envModel || DEFAULT_CODEX_MODEL;
+  const envModel = process.env[CODEX_DEFAULT_MODEL_ENV_VAR];
+  const defaultModel = getConfiguredDefaultModel();

🤖 Prompt for AI Agents

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

In `@src/types.ts` around lines 34 - 45, The code duplicates the default-model
lookup logic (process.env[CODEX_DEFAULT_MODEL_ENV_VAR] || DEFAULT_CODEX_MODEL)
using local variables envModel/defaultModel; extract that logic into a shared
helper (e.g., getDefaultModel or resolveDefaultModel) and replace the inline
logic in src/types.ts (where envModel/defaultModel are used and messages built)
and the corresponding use in handlers.ts so both call the helper; ensure the
helper exports the resolved value or a function that returns the default model
and update the message construction in the block that currently references
defaultModel to call the helper instead.

🤖 Prompt for all review comments with AI agents

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

Nitpick comments:
In `@src/types.ts`:
- Around line 34-45: The code duplicates the default-model lookup logic
(process.env[CODEX_DEFAULT_MODEL_ENV_VAR] || DEFAULT_CODEX_MODEL) using local
variables envModel/defaultModel; extract that logic into a shared helper (e.g.,
getDefaultModel or resolveDefaultModel) and replace the inline logic in
src/types.ts (where envModel/defaultModel are used and messages built) and the
corresponding use in handlers.ts so both call the helper; ensure the helper
exports the resolved value or a function that returns the default model and
update the message construction in the block that currently references
defaultModel to call the helper instead.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 7d0d0f63-796b-4611-9dd2-fe80aefbdb7a

📥 Commits

Reviewing files that changed from the base of the PR and between 00b6bf6 and a6892ab.

📒 Files selected for processing (1)

• src/types.ts