import { McpServer } from '@modelcontextprotocol/sdk/server/mcp.js';
import { readFileSync } from 'node:fs';
import { z } from 'zod';
import { FEATURES_PATH } from './suggest-feature.js';
import type { FeatureSuggestion } from './suggest-feature.js';
const MAX_RESULTS = 10;
export function registerListFeaturesTool(server: McpServer): void {
server.registerTool(
'gerbil_list_features',
{
title: 'List Feature Suggestions',
description:
'Search or list existing feature suggestions. ' +
'If query is provided, searches by tags, title, and description. ' +
'If no query, returns all suggestions.',
inputSchema: {
features_path: z
.string()
.optional()
.describe(
'Absolute path to a JSON features file. If omitted, reads the gerbil-mcp repo features.json.',
),
query: z
.string()
.optional()
.describe('Search keywords to filter suggestions (e.g. "module batch")'),
},
},
async ({ features_path: explicitPath, query }) => {
const features_path = explicitPath || FEATURES_PATH;
// Load features
let features: FeatureSuggestion[] = [];
try {
const raw = readFileSync(features_path, 'utf-8');
const parsed = JSON.parse(raw);
if (Array.isArray(parsed)) {
features = parsed;
}
} catch {
// File missing or invalid — treat as empty
}
if (features.length === 0) {
return {
content: [
{
type: 'text' as const,
text: 'No feature suggestions found.',
},
],
};
}
// If no query, return all
if (!query || query.trim().length === 0) {
const lines = formatFeatures(features);
return {
content: [
{
type: 'text' as const,
text: `${features.length} feature suggestion(s):\n\n${lines}`,
},
],
};
}
// Keyword search
const words = query
.toLowerCase()
.split(/\s+/)
.filter((w) => w.length > 0);
const scored = features.map((feature) => {
let score = 0;
for (const word of words) {
// Tags: weight 5
for (const tag of feature.tags) {
if (tag.includes(word) || word.includes(tag)) score += 5;
}
// Title: weight 3
if (feature.title.toLowerCase().includes(word)) score += 3;
// Description: weight 1
if (feature.description.toLowerCase().includes(word)) score += 1;
}
return { feature, score };
});
const matches = scored
.filter((s) => s.score > 0)
.sort((a, b) => b.score - a.score)
.slice(0, MAX_RESULTS);
if (matches.length === 0) {
return {
content: [
{
type: 'text' as const,
text: `No feature suggestions matching "${query}". There are ${features.length} total suggestion(s).`,
},
],
};
}
const lines = formatFeatures(matches.map((m) => m.feature));
return {
content: [
{
type: 'text' as const,
text: `Found ${matches.length} suggestion(s) matching "${query}":\n\n${lines}`,
},
],
};
},
);
}
function formatFeatures(features: FeatureSuggestion[]): string {
return features
.map((f) => {
const votes = f.votes ?? 0;
const parts = [
`## ${f.title}`,
`ID: ${f.id}`,
`Impact: ${f.impact} | Votes: ${votes}`,
`Tags: ${f.tags.join(', ')}`,
`Description: ${f.description}`,
`Use case: ${f.use_case}`,
`Example: ${f.example_scenario}`,
`Token reduction: ${f.estimated_token_reduction}`,
];
return parts.join('\n');
})
.join('\n\n');
}
